| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:CommonStockValue | ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | NA | 0.0 | NA | NA | NA | NA | NA | 1e-05 | NA | 1e-05 | NA | NA | NA |
| us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding us-gaap:StatementClassOfStock us-gaap:CommonClassA | ▄▄ | 35.0 | 35.0 | NA | NA | 35.0 | 35.0 | NA | 35.0 | 35.0 | 35.0 | 35.0 | 35.0 | 35.0 | 49.0 | 35.0 | 35.0 | 49.0 | 49.0 | 35.0 | 35.0 | 49.0 | 49.0 | 35.0 | NA | 35.0 | 35.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding us-gaap:StatementClassOfStock us-gaap:CommonClassC | ▄▄ | 82.0 | 82.0 | NA | NA | 81.0 | 80.0 | NA | 75.0 | 75.0 | 73.0 | 73.0 | 73.0 | 69.0 | 78.0 | 65.0 | 65.0 | 75.0 | 74.0 | 63.0 | 63.0 | 73.0 | 73.0 | 63.0 | NA | 63.0 | 35.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:WeightedAverageNumberOfSharesOutstandingBasic us-gaap:StatementClassOfStock us-gaap:CommonClassC | ▄▄ | 82.0 | 82.0 | NA | NA | 81.0 | 80.0 | NA | 75.0 | 73.0 | 73.0 | 73.0 | 73.0 | 69.0 | 67.0 | 65.0 | 65.0 | 64.0 | 63.0 | 63.0 | 63.0 | 63.0 | 63.0 | 63.0 | 63.0 | 63.0 | 35.0 | 35.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassA | NA | NA | 35.0 | 35.0 | 35.0 | 35.0 | 35.0 | NA | 35.0 | 35.0 | 35.0 | NA | 35.0 | NA | 35.0 | NA | NA | NA | 35.0 | NA | NA | NA | 35.0 | 35.0 | 35.0 | 35.0 | 35.0 | NA | 31.0 | 23.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassC | NA | NA | 82.0 | 81.0 | 81.0 | 80.0 | 79.0 | NA | NA | 73.0 | 73.0 | NA | NA | NA | 65.0 | NA | NA | NA | 63.0 | NA | NA | NA | 63.0 | 63.0 | 63.0 | 35.0 | 35.0 | NA | 31.0 | 23.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:EarningsPerShareBasic us-gaap:StatementClassOfStock us-gaap:CommonClassA | ▁█ | 0.18 | 0.3 | NA | NA | 0.27 | 0.41 | NA | NA | 0.36 | -0.22 | NA | NA | 0.2 | 0.77 | NA | NA | 0.3 | 0.29 | NA | NA | 0.34 | 0.33 | NA | NA | 0.18 | 0.15 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:EarningsPerShareBasic us-gaap:StatementClassOfStock us-gaap:CommonClassC | ▁█ | 0.18 | 0.3 | NA | NA | 0.27 | 0.41 | NA | NA | 0.36 | -0.22 | NA | NA | 0.2 | 0.77 | 0.16 | NA | 0.3 | 0.29 | -0.03 | -0.14 | 0.34 | 0.33 | NA | 0.12 | 0.18 | 0.15 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:EarningsPerShareDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassA | ▁█ | 0.18 | 0.3 | NA | NA | 0.27 | 0.41 | NA | NA | 0.36 | -0.22 | NA | -0.63 | 0.2 | 0.61 | 0.16 | -0.71 | 0.27 | 0.26 | -0.03 | -0.14 | 0.3 | 0.29 | 0.05 | NA | 0.18 | 0.15 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:EarningsPerShareDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassC | ▁█ | 0.18 | 0.3 | NA | NA | 0.27 | 0.41 | NA | NA | 0.36 | -0.22 | NA | -0.63 | 0.2 | 0.7 | 0.16 | -0.71 | 0.29 | 0.28 | -0.03 | -0.14 | 0.32 | 0.31 | 0.05 | NA | 0.18 | 0.15 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:EarningsPerShareBasicAndDiluted | NA | NA | 0.03 | NA | NA | NA | -0.26 | NA | NA | NA | -0.18 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | -0.15 | -0.030000000000000027 | 0.2 | NA | 0.18 | 0.17999999999999994 | 0.39 | NA | NA | NA | NA | NA | NA | |
| us-gaap:EarningsPerShareBasicAndDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassA | NA | NA | 0.03 | -0.21 | 0.27 | 0.41 | -0.26 | -0.060000000000000005 | 0.37 | -0.22 | -0.18 | NA | NA | NA | 0.16 | NA | NA | 0.29000000000000004 | -0.03 | NA | NA | 0.33 | 0.05 | 0.12 | 0.18 | 0.15 | -0.07 | -0.010000000000000009 | 0.1 | 0.13 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:EarningsPerShareBasicAndDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassC | NA | NA | 0.03 | -0.2 | 0.27 | 0.41 | -0.26 | -0.06 | -0.36 | -0.22 | -0.18 | NA | NA | NA | 0.16 | NA | NA | 0.29000000000000004 | -0.03 | NA | NA | 0.33 | 0.05 | 0.12 | 0.18 | 0.15 | -0.07 | -0.010000000000000009 | 0.1 | 0.13 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cost Ratio us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:ConventionalGeneration | █▆▅▇█▆▅▄▃▂▁▂▂ | 118.0 | 109.0 | 102.0 | 111.0 | 116.0 | 107.0 | 103.0 | 93.0 | 90.0 | 84.0 | 79.0 | 86.0 | 87.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Cost Ratio us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Renewables | ▆█▁▃▅▆▂▁▄▄▁▂▄ | 179.0 | 222.0 | 86.0 | 125.0 | 157.0 | 180.0 | 107.0 | 93.0 | 151.0 | 153.0 | 88.0 | 99.0 | 152.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Cost Ratio us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Thermal | ▆▄▄▂█▁▃▄▆▃▄▃▆ | 54.0 | 49.0 | 49.0 | 44.0 | 59.0 | 42.0 | 48.0 | 49.0 | 55.0 | 47.0 | 50.0 | 47.0 | 53.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| EBT Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:ConventionalGeneration | █▆▅▇█▆▅▄▃▂▁▂▂ | 118.0 | 109.0 | 102.0 | 111.0 | 116.0 | 107.0 | 103.0 | 93.0 | 90.0 | 84.0 | 79.0 | 86.0 | 87.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| EBT Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Thermal | ▆▄▄▂█▁▃▄▆▃▄▃▆ | 54.0 | 49.0 | 49.0 | 44.0 | 59.0 | 42.0 | 48.0 | 49.0 | 55.0 | 47.0 | 50.0 | 47.0 | 53.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Net profit Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:ConventionalGeneration | █▆▅▇█▆▅▄▃▂▁▂▂ | 118.0 | 109.0 | 102.0 | 111.0 | 116.0 | 107.0 | 103.0 | 93.0 | 90.0 | 84.0 | 79.0 | 86.0 | 87.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Net profit Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Thermal | ▆▄▄▂█▁▃▄▆▃▄▃▆ | 54.0 | 49.0 | 49.0 | 44.0 | 59.0 | 42.0 | 48.0 | 49.0 | 55.0 | 47.0 | 50.0 | 47.0 | 53.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Net profit Margin us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName cwen:DGPVHoldco3 | NA | NA | NA | NA | NA | 7.0 | 7.0 | NA | 9.0 | 8.0 | 4.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Operating Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:ConventionalGeneration | █▆▅▇█▆▅▄▃▂▁▂▂ | 118.0 | 109.0 | 102.0 | 111.0 | 116.0 | 107.0 | 103.0 | 93.0 | 90.0 | 84.0 | 79.0 | 86.0 | 87.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Operating Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Renewables | ▆█▁▃▅▆▂▁▄▄▁▂▄ | 179.0 | 222.0 | 86.0 | 125.0 | 157.0 | 180.0 | 107.0 | 93.0 | 151.0 | 153.0 | 88.0 | 99.0 | 152.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Operating Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Thermal | ▆▄▄▂█▁▃▄▆▃▄▃▆ | 54.0 | 49.0 | 49.0 | 44.0 | 59.0 | 42.0 | 48.0 | 49.0 | 55.0 | 47.0 | 50.0 | 47.0 | 53.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Operating Margin us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName cwen:DGPVHoldco3 | NA | NA | NA | NA | NA | 7.0 | 7.0 | NA | 9.0 | 8.0 | 4.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TTM Greenblatt ROC _ _ | ▆█▃▅▇█▅▄▆▆▅▅▇█▅▄▇▇▅▁▇▇▆▆▆▆▅▅▆▅▅▅▅▅▄▄ | 89.0 | 133.0 | -14.0 | 28.0 | 123.0 | 130.0 | 52.0 | 6.0 | 90.0 | 87.0 | 41.0 | 54.0 | 100.0 | 144.0 | 49.0 | 19.0 | 95.0 | 122.0 | 54.0 | -99.0 | 117.0 | 113.0 | 68.0 | 66.0 | 86.0 | 87.0 | 48.0 | 46.0 | 70.0 | 51.0 | 38.0 | 33.0 | 45.0 | 38.0 | 12.0 | 3.0 | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:ComprehensiveIncomeNetOfTax | ▅▆▅▃▆▆▃▄▆▃▃▁▅█▅▁▆▅▄▅▆▆▄▅▄▅▃▄▅▄▄ | 22.0 | 35.0 | 7.0 | -24.0 | 36.0 | 49.0 | -35.0 | -4.0 | 38.0 | -21.0 | -21.0 | -72.0 | 24.0 | 82.0 | 24.0 | -71.0 | 30.0 | 25.0 | 0.0 | 7.0 | 32.0 | 29.0 | -12.0 | 16.0 | 1.0 | 16.0 | -18.0 | -2.0 | 8.0 | 2.0 | -3.0 | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest | ▅▅▂▃▆▇▁▃▅▅▄▄▇▆▅▄▆▆▅▁▇▆▄▆▅▇▄▄▇▆▆█▆█ | 6.0 | -3.0 | -72.0 | -48.0 | 14.0 | 31.0 | -84.0 | -39.0 | -4.0 | -10.0 | -28.0 | -27.0 | 31.0 | 21.0 | -11.0 | -24.0 | 17.0 | 14.0 | -7.0 | -84.0 | 30.0 | 13.0 | -27.0 | 17.0 | 4.0 | 46.0 | -15.0 | -20.0 | 30.0 | 11.0 | 9.0 | 49.0 | 28.0 | 59.0 | NA | NA | NA | NA | NA |
| us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest | ▆▆▃▂▆▇▁▃▆▄▃▂▆█▅▁▆▆▅▂▇▆▄▅▅▇▄▄▆▅▅▆▆▇▅▅▅ | 28.0 | 32.0 | -65.0 | -72.0 | 50.0 | 80.0 | -119.0 | -43.0 | 34.0 | -31.0 | -49.0 | -99.0 | 55.0 | 103.0 | 17.0 | -105.0 | 48.0 | 39.0 | 5.0 | -77.0 | 68.0 | 42.0 | -39.0 | 13.0 | 5.0 | 62.0 | -33.0 | -22.0 | 38.0 | 22.0 | 12.0 | 32.0 | 37.0 | 60.0 | 12.0 | 6.0 | 1.0 | NA | NA |
| us-gaap:CostOfRevenue | █▇▇▆▆▆▆▆▆▅▅▅▅▅▆▆▅▅▅▄▅▅▅▇▄▄▅▃▃▂▃▂▁▁▁▁▁ | 117.0 | 107.0 | 110.0 | 91.0 | 95.0 | 87.0 | 93.0 | 93.0 | 86.0 | 79.0 | 84.0 | 85.0 | 84.0 | 74.0 | 89.0 | 87.0 | 78.0 | 77.0 | 84.0 | 68.0 | 76.0 | 75.0 | 83.0 | 101.0 | 69.0 | 67.0 | 75.0 | 57.0 | 52.0 | 45.0 | 53.0 | 35.0 | 33.0 | 32.0 | 29.0 | 31.0 | 28.0 | NA | NA |
| us-gaap:CostsAndExpenses | ▆▆▆▆▅▅▅▆▅▅▄▄▅▄▄▆▄▄▄█▄▄▄▅▃▃▃▃▂▂▂▁▁▁▁▁▁ | 262.0 | 247.0 | 251.0 | 252.0 | 209.0 | 199.0 | 206.0 | 229.0 | 206.0 | 197.0 | 176.0 | 175.0 | 192.0 | 163.0 | 176.0 | 230.0 | 170.0 | 162.0 | 164.0 | 331.0 | 155.0 | 145.0 | 152.0 | 207.0 | 123.0 | 130.0 | 132.0 | 102.0 | 91.0 | 83.0 | 72.0 | 53.0 | 50.0 | 44.0 | 41.0 | 39.0 | 36.0 | NA | NA |
| us-gaap:GainsLossesOnExtinguishmentOfDebt | ██▁▆▇██▆███▇██████████ | 0.0 | 0.0 | -42.0 | -15.0 | -6.0 | 0.0 | -3.0 | -15.0 | 0.0 | -1.0 | 0.0 | -7.0 | 0.0 | 0.0 | 0.0 | -1.0 | 0.0 | 0.0 | -2.0 | 0.0 | 0.0 | 0.0 | NA | 0.0 | -2.0 | -7.0 | NA | 0.0 | 0.0 | 0.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:ConsolidationItems us-gaap:CorporateNonSegment | ██▁███▇▅██ | 0.0 | 0.0 | -41.0 | 0.0 | 0.0 | 0.0 | -3.0 | -15.0 | 0.0 | 0.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,cwen:Renewables | ███▁▅█████ | 0.0 | 0.0 | -1.0 | -15.0 | -6.0 | 0.0 | 0.0 | 0.0 | 0.0 | -1.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:DebtInstrument cwen:A5.75SeniorNotesdue2025 | ▄ | 0.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:GeneralAndAdministrativeExpense | ▇▇▇▃▆█▆▆▅▅▄▂▄▄▄▄▃▄▃▄▃▂▂▂▂▂▂▁▂▂▂▂▁▂▂ | 10.0 | 10.0 | 10.0 | 4.0 | 9.0 | 12.0 | 9.0 | 9.0 | 7.0 | 7.0 | 6.0 | 3.0 | 6.0 | 6.0 | 5.0 | 5.0 | 4.0 | 6.0 | 4.0 | 6.0 | 4.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 1.0 | 3.0 | 2.0 | 2.0 | 2.0 | 1.0 | 2.0 | 2.0 | NA | NA | NA | NA |
| us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | ▆▆▃▃▇█▂▄▆▄▄▄▇█▅▄▇▇▅▁▇▇▅▅▆▆▅▅▆▆▆▆▆▆▅▅▆▅ | 26.0 | 39.0 | -96.0 | -78.0 | 51.0 | 102.0 | -129.0 | -42.0 | 24.0 | -32.0 | -54.0 | -46.0 | 60.0 | 103.0 | -1.0 | -51.0 | 49.0 | 53.0 | -2.0 | -152.0 | 60.0 | 70.0 | 2.0 | 0.0 | 42.0 | 45.0 | -20.0 | -21.0 | 41.0 | 36.0 | 21.0 | 27.0 | 45.0 | 34.0 | 11.0 | 5.0 | 12.0 | -2.0 | NA |
| us-gaap:IncomeTaxExpenseBenefit | ▃▄▂▃▄▅▁▄▂▄▃▇▄▄▃█▄▄▃▁▄▄▃▄▄▄▃▂▄▃▃▃▄▃▃▃▄ | 1.0 | 7.0 | -20.0 | -5.0 | 9.0 | 26.0 | -22.0 | 6.0 | -11.0 | 4.0 | -7.0 | 45.0 | 11.0 | 7.0 | -1.0 | 57.0 | 8.0 | 8.0 | -1.0 | -26.0 | 13.0 | 12.0 | 0.0 | 4.0 | 8.0 | 4.0 | -4.0 | -11.0 | 10.0 | 2.0 | 3.0 | 3.0 | 5.0 | 0.0 | 0.0 | 0.0 | 8.0 | NA | NA |
| us-gaap:InterestExpense | ▄▅▃▄▄▅█▄▅▆▅▅▄▄▃▄▄▅▄▃▄▄▄▄▄▃▄▄▃▂▂▁▁▁▁▁▁ | 84.0 | 103.0 | 45.0 | 70.0 | 85.0 | 93.0 | 167.0 | 67.0 | 106.0 | 130.0 | 101.0 | 106.0 | 74.0 | 71.0 | 55.0 | 69.0 | 75.0 | 86.0 | 76.0 | 61.0 | 71.0 | 62.0 | 68.0 | 62.0 | 62.0 | 44.0 | 70.0 | 69.0 | 41.0 | 29.0 | 19.0 | 11.0 | 13.0 | 6.0 | 5.0 | 3.0 | 5.0 | NA | NA |
| us-gaap:NetIncomeLoss | ▆▇▄▁▇█▁▃▇▁▂ | 21.0 | 35.0 | 3.0 | -25.0 | 32.0 | 47.0 | -29.0 | -6.0 | 39.0 | -24.0 | -20.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 6.0 | 6.0 | NA | NA | 9.0 | 33.0 | NA | NA | NA | -1.0 | NA |
| us-gaap:NetIncomeLossAttributableToNoncontrollingInterest | ▇▆▃▄▇█▃▄▆▆▅▅█▇▆▅▇▇▆▁▇█▆▇▇█▆▇█▇ | 4.0 | -3.0 | -79.0 | -48.0 | 10.0 | 29.0 | -78.0 | -42.0 | -4.0 | -12.0 | -27.0 | -23.0 | 28.0 | 17.0 | -20.0 | -28.0 | 11.0 | 17.0 | -10.0 | -113.0 | 8.0 | 26.0 | -3.0 | 5.0 | 17.0 | 31.0 | -11.0 | 6.0 | 25.0 | 19.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic | NA | NA | NA | -25.0 | 32.0 | 47.0 | -29.0 | -6.0 | 39.0 | -24.0 | -20.0 | -68.0 | 21.0 | 79.0 | 16.0 | -70.0 | 29.0 | 28.0 | -3.0 | -13.0 | 33.0 | 32.0 | 5.0 | 11.0 | 17.0 | 10.0 | -5.0 | 0.0 | 6.0 | 6.0 | 4.0 | 4.0 | 9.0 | NA | NA | NA | NA | NA | NA | |
| us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassA | NA | NA | NA | NA | 9.0 | NA | NA | NA | 12.0 | -8.0 | NA | NA | 7.0 | 30.0 | NA | NA | 13.0 | 13.0 | NA | NA | 15.0 | 14.0 | NA | NA | 6.0 | 5.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted us-gaap:StatementClassOfStock us-gaap:CommonClassC | NA | NA | NA | NA | 22.0 | NA | NA | NA | 27.0 | -16.0 | NA | NA | 14.0 | 55.0 | NA | NA | 21.0 | 21.0 | NA | NA | 24.0 | 23.0 | NA | NA | 11.0 | 5.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:NonoperatingIncomeExpense | ▆▄▅▄▅▇▁▆▅▃▄▄▆▆▆▆▆▅▆▆▆▆▅▆▆▆▅▅▇▇▇██████ | -63.0 | -94.0 | -82.0 | -106.0 | -72.0 | -28.0 | -181.0 | -48.0 | -66.0 | -119.0 | -95.0 | -100.0 | -40.0 | -41.0 | -50.0 | -63.0 | -46.0 | -69.0 | -56.0 | -53.0 | -57.0 | -43.0 | -66.0 | -56.0 | -44.0 | -42.0 | -68.0 | -67.0 | -29.0 | -15.0 | -17.0 | -6.0 | 0.0 | -3.0 | -1.0 | 2.0 | 1.0 | NA | NA |
| us-gaap:OperatingIncomeLoss | ▆█▃▅▇█▅▄▆▆▅▅▇█▅▄▇▇▅▁▇▇▆▆▆▆▅▅▆▅▅▅▅▅▄▄▄▄▄ | 89.0 | 133.0 | -14.0 | 28.0 | 123.0 | 130.0 | 52.0 | 6.0 | 90.0 | 87.0 | 41.0 | 54.0 | 100.0 | 144.0 | 49.0 | 19.0 | 95.0 | 122.0 | 54.0 | -99.0 | 117.0 | 113.0 | 68.0 | 66.0 | 86.0 | 87.0 | 48.0 | 46.0 | 70.0 | 51.0 | 38.0 | 33.0 | 45.0 | 38.0 | 12.0 | 3.0 | 11.0 | 8.0 | 9.0 |
| us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax | ▃▁█ | 3.0 | 0.0 | 11.0 | NA | 8.0 | 4.0 | -12.0 | 5.0 | -1.0 | 5.0 | -2.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:OtherComprehensiveIncomeLossNetOfTax | ▃▁█ | 3.0 | 0.0 | 11.0 | NA | 8.0 | 4.0 | -12.0 | 5.0 | -1.0 | 5.0 | -2.0 | -8.0 | 6.0 | 7.0 | 17.0 | 3.0 | 7.0 | -6.0 | 6.0 | 49.0 | 21.0 | -16.0 | -41.0 | 17.0 | -29.0 | 21.0 | -17.0 | -12.0 | 7.0 | -12.0 | -6.0 | 8.0 | -3.0 | 25.0 | 1.0 | 1.0 | -3.0 | NA | NA |
| us-gaap:OtherNonoperatingIncomeExpense | ▃▃▃▄▁▁▄▆▄▃▆█▄▃▃▃▃▃▃▁▃▃▁▁▃▁▃▃▃▁▃▃▃▃▁▃▁ | 1.0 | 1.0 | 1.0 | 2.0 | 0.0 | 0.0 | 2.0 | 3.0 | 2.0 | 1.0 | 3.0 | 4.0 | 2.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 0.0 | 0.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 0.0 | NA | NA |
| us-gaap:ProfitLoss | ▆▆▃▃▆▇▂▃▆▄▃▂▇█▅▂▆▆▅▁▆▇▅▅▆▆▄▅▆▆▆▆▆▆▅▅▅▅▅ | 25.0 | 32.0 | -76.0 | -73.0 | 42.0 | 76.0 | -107.0 | -48.0 | 35.0 | -36.0 | -47.0 | -91.0 | 49.0 | 96.0 | 0.0 | -98.0 | 41.0 | 45.0 | -1.0 | -126.0 | 47.0 | 58.0 | 2.0 | 13.0 | 34.0 | 41.0 | -16.0 | -10.0 | 31.0 | 34.0 | 18.0 | 24.0 | 40.0 | 34.0 | 11.0 | 5.0 | 4.0 | -1.0 | 5.0 |
| us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax | ▇█▅▆▇▇▁▅▁▁▁▅▁▁▁▅▆▆▅▅▆▅▅▄▄▅▄▃▃▃▂▂▂▂▁▁▁▁▁ | 351.0 | 380.0 | 237.0 | 280.0 | 332.0 | 329.0 | 55.0 | 235.0 | 64.0 | 57.0 | 55.0 | 229.0 | 63.0 | 58.0 | 61.0 | 231.0 | 265.0 | 284.0 | 218.0 | 232.0 | 272.0 | 258.0 | 220.0 | 209.0 | 209.0 | 217.0 | 180.0 | 148.0 | 161.0 | 134.0 | 110.0 | 86.0 | 95.0 | 79.0 | 53.0 | 42.0 | 47.0 | 42.0 | 44.0 |
| us-gaap:Revenues | ▇█▅▆▇▇▅▅▆▆▅▅▆▆▅▅▆▆▅▅▆▅▅▄▄▅▄▃▃▃▂▂▂▂▁▁▁▁▁ | 351.0 | 380.0 | 237.0 | 280.0 | 332.0 | 329.0 | 258.0 | 235.0 | 296.0 | 284.0 | 217.0 | 229.0 | 292.0 | 307.0 | 225.0 | 231.0 | 265.0 | 284.0 | 218.0 | 232.0 | 272.0 | 258.0 | 220.0 | 209.0 | 209.0 | 217.0 | 180.0 | 148.0 | 161.0 | 134.0 | 110.0 | 86.0 | 95.0 | 79.0 | 53.0 | 42.0 | 47.0 | 42.0 | 44.0 |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
|---|
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:Assets | ███▇▆▆▆▆▆▆▆▆▆▆▅▅▆▆▆▆▆▅▅▅▅▅▄▄▄▂▁▁▁▁ | 11780.0 | 11881.0 | 11848.0 | 10592.0 | 9725.0 | 9736.0 | 9555.0 | 9700.0 | 8838.0 | 8731.0 | 8465.0 | 8500.0 | 8500.0 | 8448.0 | 8362.0 | 8283.0 | 8442.0 | 8513.0 | 8580.0 | 8383.0 | 8482.0 | 7607.0 | 7659.0 | 7775.0 | 6989.0 | 7208.0 | 6595.0 | 5752.0 | 5899.0 | 3236.0 | 2534.0 | 2313.0 | 2331.0 | 2074.0 | NA | 1964.0 | NA | NA | NA |
| us-gaap:Liabilities | ███▇▇▇▇▇▆▆▆▆▅▅▆▅▅▆▆▅▅▄▅▅▄▄▅▄▄▂▁▁▁ | 8825.0 | 8878.0 | 8853.0 | 7877.0 | 7488.0 | 7504.0 | 7291.0 | 7437.0 | 6792.0 | 6677.0 | 6320.0 | 6276.0 | 6125.0 | 6161.0 | 6236.0 | 6145.0 | 6143.0 | 6177.0 | 6242.0 | 6013.0 | 6014.0 | 5050.0 | 5098.0 | 5143.0 | 4837.0 | 5002.0 | 5254.0 | 4272.0 | 4285.0 | 2163.0 | 1503.0 | 1302.0 | 1340.0 | NA | NA | 1124.0 | NA | NA | NA |
| us-gaap:LiabilitiesAndStockholdersEquity | ███▅▃▃▃▃▁▁ | 11780.0 | 11881.0 | 11848.0 | 10592.0 | 9725.0 | 9736.0 | 9555.0 | 9700.0 | 8838.0 | 8731.0 | NA | 8500.0 | 8500.0 | 8448.0 | 8362.0 | 8283.0 | 8442.0 | 8513.0 | 8580.0 | 8383.0 | 8482.0 | 7607.0 | 7659.0 | 7775.0 | 6989.0 | 7208.0 | 6595.0 | 5752.0 | 5899.0 | 3236.0 | 2534.0 | 2313.0 | 2331.0 | NA | NA | 1964.0 | NA | NA | NA |
| us-gaap:StockholdersEquity dei:LegalEntity,us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName,us-gaap:CapitalUnitsByClass cwen:ThirdPartyInvestor,cwen:RattlesnakeTEHoldcoLLC,us-gaap:CapitalUnitClassA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AssetsCurrent | █▇▇▆▇▆▅▅▆▄▄▇▅▄▃▄▄▄▄▆▅▂▂▂▃▄▂▅▅▁▄▂▃ | 853.0 | 767.0 | 734.0 | 708.0 | 773.0 | 654.0 | 554.0 | 608.0 | 619.0 | 498.0 | 456.0 | 756.0 | 603.0 | 472.0 | 425.0 | 482.0 | 520.0 | 491.0 | 476.0 | 645.0 | 531.0 | 319.0 | 284.0 | 318.0 | 376.0 | 491.0 | 293.0 | 539.0 | 555.0 | 196.0 | 502.0 | 267.0 | 408.0 | NA | NA | 81.0 | NA | NA | NA |
| us-gaap:CashAndCashEquivalentsAtCarryingValue | ▄▃▃▅▇▄▃▃▃▂▃█▅▃▄▃▄▄▄▆▄▂▂▃▃▆▃▇▇▂█▁▃▁▁▁▁ | 189.0 | 138.0 | 144.0 | 268.0 | 359.0 | 175.0 | 110.0 | 155.0 | 148.0 | 93.0 | 117.0 | 407.0 | 232.0 | 130.0 | 173.0 | 148.0 | 179.0 | 181.0 | 213.0 | 317.0 | 200.0 | 89.0 | 76.0 | 111.0 | 125.0 | 281.0 | 114.0 | 391.0 | 372.0 | 87.0 | 420.0 | 36.0 | 121.0 | 18.0 | 23.0 | 22.0 | 30.0 | NA | NA |
| us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents | ▇▆▅▆▇▅▄▅▄▃▃█▄▂▂▃▃▃▃▆▃▁ | 555.0 | 470.0 | 431.0 | 465.0 | 537.0 | 416.0 | 380.0 | 417.0 | 397.0 | 296.0 | 298.0 | 583.0 | 389.0 | 269.0 | 277.0 | 316.0 | 319.0 | 295.0 | 323.0 | 487.0 | 338.0 | 213.0 | NA | 242.0 | NA | NA | NA | 573.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:AccountsReceivableNetCurrent | ██▆▅▆▆▄▄▅▅▃▄▅▅▃▃▅▄▃▃▄▄▃▃▄▄▂▂▃▂▁▁ | 203.0 | 203.0 | 159.0 | 143.0 | 156.0 | 161.0 | 99.0 | 116.0 | 141.0 | 126.0 | 91.0 | 104.0 | 141.0 | 132.0 | 82.0 | 95.0 | 126.0 | 119.0 | 82.0 | 91.0 | 115.0 | 109.0 | 85.0 | 95.0 | 104.0 | 98.0 | 63.0 | 67.0 | 80.0 | 56.0 | 38.0 | 40.0 | NA | NA | NA | 22.0 | NA | NA | NA |
| us-gaap:InventoryNet | ▇▇▇▇▇▇▇▆▇█▆▆▆▆▆▆▆▇▆▆▆▆▅▆▅▄▄▃▂▂▂▂▁ | 42.0 | 43.0 | 43.0 | 42.0 | 42.0 | 41.0 | 41.0 | 40.0 | 43.0 | 49.0 | 40.0 | 40.0 | 39.0 | 39.0 | 39.0 | 39.0 | 38.0 | 41.0 | 40.0 | 39.0 | 37.0 | 35.0 | 34.0 | 35.0 | 30.0 | 29.0 | 27.0 | 18.0 | 17.0 | 14.0 | 15.0 | 14.0 | 9.0 | NA | NA | 5.0 | NA | NA | NA |
| us-gaap:PrepaidExpenseAndOtherAssetsCurrent | ▄▄█▅▃▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▃▂▂▂▂▁▁▂▂ | 51.0 | 50.0 | 101.0 | 58.0 | 38.0 | 36.0 | 33.0 | 33.0 | 34.0 | 26.0 | 27.0 | 29.0 | 31.0 | 26.0 | 18.0 | 19.0 | 22.0 | 21.0 | 19.0 | 16.0 | 21.0 | 22.0 | 20.0 | 22.0 | 25.0 | 19.0 | 18.0 | 19.0 | 22.0 | 7.0 | 4.0 | 17.0 | 18.0 | NA | NA | 2.0 | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AssetsNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName cwen:DesertSunlight | NA | NA | NA | 1244.0 | NA | 1271.0 | NA | 1296.0 | NA | NA | NA | 1298.0 | NA | NA | NA | 1350.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:AssetsNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName cwen:GenConn | NA | NA | NA | 344.0 | NA | NA | NA | 342.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:AssetsNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName cwen:InvestmentsOther | NA | NA | NA | 2201.0 | NA | NA | NA | 2514.0 | NA | NA | NA | 2511.0 | NA | NA | NA | 2621.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:PropertyPlantAndEquipmentGross | NA | NA | NA | 9540.0 | NA | NA | NA | 7943.0 | NA | NA | NA | 6835.0 | NA | NA | NA | 6489.0 | NA | NA | NA | 6411.0 | NA | NA | 5779.0 | 5757.0 | 4933.0 | 4927.0 | 4821.0 | 3795.0 | 3542.0 | 2488.0 | 1711.0 | 1705.0 | 1636.0 | 1626.0 | NA | 1713.0 | NA | NA | NA | |
| us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:AssetsLeasedToOthers | NA | NA | NA | 7201.0 | 6975.0 | 6974.0 | 7020.0 | 6942.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:ConstructionInProgress | NA | NA | NA | 62.0 | NA | NA | NA | 94.0 | NA | NA | NA | 26.0 | NA | NA | NA | 238.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 7.0 | 11.0 | 8.0 | 6.0 | 5.0 | 2.0 | NA | 930.0 | NA | NA | NA | |
| us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LandAndLandImprovements | NA | NA | NA | 224.0 | NA | NA | NA | 173.0 | NA | NA | NA | 171.0 | NA | NA | NA | 166.0 | NA | NA | NA | 171.0 | NA | NA | 151.0 | 151.0 | 92.0 | 87.0 | 87.0 | 87.0 | NA | NA | NA | 45.0 | 34.0 | 35.0 | NA | 30.0 | NA | NA | NA | |
| us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:SupportEquipmentAndFacilities | NA | NA | NA | 9254.0 | NA | NA | NA | 7676.0 | NA | NA | NA | 6638.0 | NA | NA | NA | 6289.0 | NA | NA | NA | 6215.0 | NA | NA | 5602.0 | 5597.0 | 4837.0 | 4832.0 | 4717.0 | 3701.0 | NA | NA | NA | 1654.0 | NA | NA | NA | 680.0 | NA | NA | NA | |
| us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment | ██▇▇▆▆▆▆▆▅▅▅▅▅▄▄▄▄▃▃▃▃▃▃▂▂▂▁▁▁▁▁▁▁ | 2700.0 | 2573.0 | 2447.0 | 2323.0 | 2135.0 | 2036.0 | 1970.0 | 1880.0 | 1830.0 | 1731.0 | 1674.0 | 1590.0 | 1507.0 | 1428.0 | 1358.0 | 1285.0 | 1189.0 | 1102.0 | 1025.0 | 951.0 | 1002.0 | 832.0 | 767.0 | 701.0 | 499.0 | 449.0 | 391.0 | 308.0 | 266.0 | 233.0 | 181.0 | 164.0 | 149.0 | 134.0 | NA | 115.0 | NA | NA | NA |
| us-gaap:PropertyPlantAndEquipmentNet | ████▆▇▆▆▆▆▅▅▅▅▅▅▅▅▆▆▆▅▅▅▄▄▄▃▃▂▁▁▁▁ | 7438.0 | 7537.0 | 7490.0 | 7217.0 | 6165.0 | 6256.0 | 6001.0 | 6063.0 | 5562.0 | 5602.0 | 5355.0 | 5245.0 | 5306.0 | 5376.0 | 5340.0 | 5204.0 | 5247.0 | 5322.0 | 5390.0 | 5460.0 | 5711.0 | 4947.0 | 5012.0 | 5056.0 | 4434.0 | 4478.0 | 4430.0 | 3487.0 | 3276.0 | 2255.0 | 1530.0 | 1541.0 | 1487.0 | 1492.0 | NA | 1598.0 | NA | NA | NA |
| us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures dei:LegalEntity cwen:ClearwayEnergyInc. | NA | NA | NA | 2612.0 | NA | NA | NA | 2173.0 | NA | NA | NA | 2182.0 | NA | NA | NA | 2029.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:ConsolidatedEntities cwen:DGPVHoldco1And2 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:FiniteLivedIntangibleAssetsNet | ███▅▅▅▅▅▄▄▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▆▁▁▁▁ | 2154.0 | 2188.0 | 2223.0 | 1370.0 | 1371.0 | 1393.0 | 1406.0 | 1428.0 | 1103.0 | 1121.0 | 1139.0 | 1156.0 | 1177.0 | 1192.0 | 1210.0 | 1228.0 | 1234.0 | 1251.0 | 1268.0 | 1286.0 | 1303.0 | 1321.0 | 1338.0 | 1362.0 | 1377.0 | 1389.0 | 1403.0 | 1266.0 | 1517.0 | 105.0 | 85.0 | 86.0 | 27.0 | NA | NA | 30.0 | NA | NA | NA |
| us-gaap:DeferredTaxAssetsLiabilitiesNet | NA | NA | NA | 104.0 | NA | NA | NA | 92.0 | NA | NA | NA | 57.0 | NA | NA | NA | 128.0 | NA | NA | NA | 216.0 | NA | NA | NA | 170.0 | NA | NA | NA | 134.0 | NA | NA | NA | 146.0 | NA | NA | NA | -3.0 | NA | NA | NA | |
| us-gaap:OperatingLeaseRightOfUseAsset | ███▇▄▄▃▃▁▁ | 346.0 | 349.0 | 348.0 | 337.0 | 256.0 | 257.0 | 221.0 | 223.0 | 191.0 | 183.0 | NA | 0.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:OtherAssetsNoncurrent | ▆██▆▄▆▆▆▆▅▇▆▅▄▄▃▃▄▃▂▂▃▃▃▆█▇▅▅▅▁▁▁ | 104.0 | 144.0 | 139.0 | 114.0 | 75.0 | 110.0 | 108.0 | 103.0 | 109.0 | 100.0 | 128.0 | 106.0 | 92.0 | 82.0 | 73.0 | 63.0 | 56.0 | 74.0 | 66.0 | 51.0 | 47.0 | 66.0 | 58.0 | 61.0 | 114.0 | 144.0 | 123.0 | 99.0 | 93.0 | 93.0 | 32.0 | 27.0 | 26.0 | NA | NA | 21.0 | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AccountsPayableCurrent | ▃▃█▅▂▁ | 58.0 | 59.0 | 93.0 | 72.0 | 46.0 | 41.0 | NA | 74.0 | NA | 62.0 | 55.0 | 45.0 | 90.0 | 40.0 | 40.0 | 27.0 | 27.0 | 23.0 | 26.0 | 23.0 | 23.0 | 21.0 | 26.0 | 23.0 | 22.0 | 23.0 | 33.0 | 19.0 | NA | NA | NA | 40.0 | NA | NA | NA | 166.0 | NA | NA | NA |
| us-gaap:LiabilitiesCurrent | ▃▃▃▃▃▂▆▇██▆▃▄▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▁ | 816.0 | 754.0 | 748.0 | 634.0 | 602.0 | 555.0 | 1714.0 | 2057.0 | 2246.0 | 2127.0 | 1787.0 | 704.0 | 1085.0 | 804.0 | 859.0 | 486.0 | 490.0 | 438.0 | 455.0 | 459.0 | 459.0 | 380.0 | 383.0 | 456.0 | 425.0 | 570.0 | 389.0 | 297.0 | 302.0 | 233.0 | 150.0 | 257.0 | 267.0 | NA | NA | 285.0 | NA | NA | NA |
| us-gaap:LongTermDebtCurrent | ▂▂▂▁▁▁▆▇██▆▂ | 545.0 | 518.0 | 500.0 | 384.0 | 361.0 | 357.0 | 1480.0 | 1824.0 | 1965.0 | 1914.0 | 1608.0 | 535.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 241.0 | 224.0 | 407.0 | 218.0 | 160.0 | 157.0 | 119.0 | 71.0 | 133.0 | 147.0 | 126.0 | NA | 58.0 | NA | NA | NA |
| us-gaap:OperatingLeaseLiabilityCurrent | NA | NA | NA | 8.0 | 7.0 | 7.0 | 7.0 | 7.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:OtherAccruedLiabilitiesCurrent | █▄▃▅▆▁▁▄ | 104.0 | 64.0 | 62.0 | 79.0 | 89.0 | 40.0 | 39.0 | 71.0 | NA | 42.0 | 35.0 | 57.0 | 96.0 | 60.0 | 58.0 | 88.0 | 95.0 | 60.0 | 55.0 | 85.0 | 94.0 | 39.0 | 53.0 | 68.0 | 79.0 | NA | NA | 61.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:LiabilitiesNoncurrent | ███▇▇▇▅▅▄▄▄▅▅▅▅▆▆▆▆▅▅▅▅▅▄▄▅▄▄▂▁▁▁ | 8009.0 | 8124.0 | 8105.0 | 7243.0 | 6886.0 | 6949.0 | 5577.0 | 5380.0 | 4546.0 | 4550.0 | 4533.0 | 5572.0 | 5040.0 | 5357.0 | 5377.0 | 5659.0 | 5653.0 | 5739.0 | 5787.0 | 5554.0 | 5555.0 | 4670.0 | 4715.0 | 4687.0 | 4412.0 | 4432.0 | 4865.0 | 3975.0 | 3983.0 | 1930.0 | 1353.0 | 1045.0 | 1073.0 | NA | NA | 839.0 | NA | NA | NA |
| us-gaap:LongTermDebt | NA | NA | NA | 7043.0 | NA | NA | NA | 6858.0 | 6179.0 | 6184.0 | 5887.0 | 6044.0 | 5870.0 | 5970.0 | 6038.0 | 5914.0 | 5901.0 | 5983.0 | 6051.0 | 5770.0 | 5704.0 | 4772.0 | 4821.0 | 4863.0 | 4509.0 | NA | NA | 4069.0 | NA | NA | NA | 1133.0 | 1167.0 | 1202.0 | NA | 807.0 | NA | NA | NA | |
| us-gaap:LongTermDebtNoncurrent | ███▇▇▇▅▅▄▄▄▆▅▆▆▆▆▆▆▆▆▅▅▅▅▅▅▄▄▂▁▁▁ | 7299.0 | 7434.0 | 7463.0 | 6585.0 | 6357.0 | 6377.0 | 5081.0 | 4956.0 | 4143.0 | 4192.0 | 4215.0 | 5447.0 | 4928.0 | 5244.0 | 5261.0 | 5531.0 | 5520.0 | 5597.0 | 5662.0 | 5426.0 | 5359.0 | 4465.0 | 4521.0 | 4562.0 | 4285.0 | 4336.0 | 4719.0 | 3890.0 | 3926.0 | 1880.0 | 1310.0 | 1000.0 | 1020.0 | NA | NA | 749.0 | NA | NA | NA |
| us-gaap:LongTermDebtAndCapitalLeaseObligations | ███▇▇▇▅▅▄▄▄▆▅▆▆▆▆▆▆▆▆▅▅▅▅▅▅▄▄▂▁▁ | 7299.0 | 7434.0 | 7463.0 | 6585.0 | 6357.0 | 6377.0 | 5081.0 | 4956.0 | 4143.0 | 4192.0 | 4225.0 | 5447.0 | 4928.0 | 5244.0 | 5261.0 | 5531.0 | 5520.0 | 5597.0 | 5662.0 | 5426.0 | 5359.0 | 4465.0 | 4521.0 | 4562.0 | 4285.0 | 4336.0 | 4719.0 | 3890.0 | 3926.0 | 1880.0 | 1310.0 | 1000.0 | NA | 1076.0 | NA | 749.0 | NA | NA | NA |
| us-gaap:MinorityInterest | ███▆▂▃▃▃▂▂▃▃▃▃▃▃▃▃▃▄▄▅▅▅▂▂▁▂▂▂▃▃▃ | 1177.0 | 1209.0 | 1199.0 | 890.0 | 355.0 | 370.0 | 463.0 | 413.0 | 298.0 | 322.0 | 373.0 | 402.0 | 440.0 | 419.0 | 371.0 | 391.0 | 437.0 | 498.0 | 508.0 | 520.0 | 622.0 | 742.0 | 753.0 | 791.0 | 348.0 | 361.0 | 131.0 | 246.0 | 279.0 | 264.0 | 385.0 | 382.0 | 413.0 | NA | NA | 0.0 | NA | NA | NA |
| us-gaap:OtherLiabilitiesNoncurrent | ████▅▅▅▅▅▅▅▅▄▄▄▄▄▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁▁ | 189.0 | 184.0 | 181.0 | 178.0 | 119.0 | 120.0 | 123.0 | 121.0 | 115.0 | 106.0 | 109.0 | 108.0 | 103.0 | 101.0 | 99.0 | 97.0 | 87.0 | 79.0 | 79.0 | 76.0 | 78.0 | 63.0 | 64.0 | 64.0 | 53.0 | 52.0 | 49.0 | 39.0 | 29.0 | 21.0 | 23.0 | 29.0 | 28.0 | NA | NA | 25.0 | NA | NA | NA |
| us-gaap:OperatingLeaseLiabilityNoncurrent | ███▇▄▄▂▃▁▁ | 361.0 | 361.0 | 354.0 | 345.0 | 260.0 | 260.0 | 222.0 | 227.0 | 193.0 | 186.0 | NA | 0.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo | NA | NA | NA | 23.0 | 18.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree | NA | NA | NA | 23.0 | 18.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour | NA | NA | NA | 23.0 | 18.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive | NA | NA | NA | 23.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive | NA | NA | NA | 476.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:StockholdersEquity dei:LegalEntity,us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName,us-gaap:CapitalUnitsByClass cwen:ThirdPartyInvestor,cwen:RattlesnakeTEHoldcoLLC,us-gaap:CapitalUnitClassA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | ███▇▆▆▆▆▆▆▆▆▇▆▆▆▆▆▆▇▇▇▇▇▆▆▄▄▅▄▃▃▃▁ | 2955.0 | 3003.0 | 2995.0 | 2715.0 | 2237.0 | 2232.0 | 2264.0 | 2263.0 | 2046.0 | 2054.0 | 2145.0 | 2224.0 | 2375.0 | 2287.0 | 2126.0 | 2138.0 | 2299.0 | 2336.0 | 2338.0 | 2370.0 | 2468.0 | 2557.0 | 2561.0 | 2632.0 | 2152.0 | 2206.0 | 1341.0 | 1480.0 | 1614.0 | 1073.0 | 1031.0 | 1011.0 | 991.0 | 0.0 | NA | 0.0 | NA | NA | NA |
| us-gaap:CommonStockValue | ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | NA | 0.0 | NA | NA | NA | NA | NA | 1e-05 | NA | 1e-05 | NA | NA | NA |
| us-gaap:AdditionalPaidInCapital | ▇▇██████▇▇▇██▇▇▇▇▇▇▇▇▇▇▇▇▇▁▁ | 1810.0 | 1848.0 | 1886.0 | 1922.0 | 1918.0 | 1934.0 | 1922.0 | 1936.0 | 1830.0 | 1852.0 | 1870.0 | 1897.0 | 1935.0 | 1859.0 | 1827.0 | 1843.0 | 1864.0 | 1842.0 | 1859.0 | 1879.0 | 1858.0 | 1835.0 | 1844.0 | 1855.0 | 1820.0 | 1852.0 | 1235.0 | 1240.0 | NA | NA | NA | 621.0 | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:RetainedEarningsAccumulatedDeficit | ▅▄▂▂▅▄▁▃▃▁▂▃▇█▄▃▇▇▆▆██▇▇▇▇▆▆▆▆▆▇▇ | -25.0 | -46.0 | -81.0 | -84.0 | -22.0 | -54.0 | -101.0 | -72.0 | -66.0 | -105.0 | -80.0 | -58.0 | 13.0 | 25.0 | -53.0 | -69.0 | 24.0 | 23.0 | -5.0 | -2.0 | 35.0 | 26.0 | 7.0 | 12.0 | 15.0 | 8.0 | -2.0 | 3.0 | 5.0 | 3.0 | 4.0 | 8.0 | 9.0 | NA | NA | 30.0 | NA | NA | NA |
| us-gaap:RetainedEarningsAccumulatedDeficit dei:LegalEntity cwen:ClearwayEnergyInc. | NA | NA | NA | -84.0 | NA | NA | NA | -72.0 | NA | NA | NA | -58.0 | NA | NA | NA | -69.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax | ▇▇▇▆▆▅▅▆▆▆▅▅▆▆▅▄▄▄▄▄▁▁▂▄▃▆▅▇▇▇███ | -8.0 | -9.0 | -10.0 | -14.0 | -15.0 | -19.0 | -21.0 | -15.0 | -17.0 | -16.0 | -19.0 | -18.0 | -14.0 | -17.0 | -20.0 | -28.0 | -27.0 | -28.0 | -25.0 | -28.0 | -48.0 | -47.0 | -44.0 | -27.0 | -32.0 | -16.0 | -23.0 | -9.0 | -6.0 | -9.0 | -2.0 | 0.0 | -2.0 | NA | NA | -24.0 | NA | NA | NA |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax dei:LegalEntity cwen:ClearwayEnergyInc. | NA | NA | NA | -14.0 | NA | NA | NA | -15.0 | NA | NA | NA | -18.0 | NA | NA | NA | -28.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncome | █▇▇▅▄▂▁▄▃▄▂▃ | -8.0 | -9.0 | -10.0 | -14.0 | -15.0 | -19.0 | -21.0 | -15.0 | -17.0 | -16.0 | -19.0 | -18.0 | NA | -17.0 | NA | -28.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AociAttributableToNoncontrollingInterest | █▁▄ | -8.0 | -10.0 | -9.0 | NA | -16.0 | -20.0 | -22.0 | NA | -19.0 | -19.0 | -21.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest | NA | NA | NA | -16.0 | NA | NA | NA | -16.0 | -19.0 | -19.0 | -21.0 | -20.0 | -16.0 | -19.0 | -23.0 | -32.0 | -36.0 | -42.0 | NA | -42.0 | -71.0 | -42.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:MinorityInterest | ███▆▂▃▃▃▂▂▃▃▃▃▃▃▃▃▃▄▄▅▅▅▂▂▁▂▂▂▃▃▃ | 1177.0 | 1209.0 | 1199.0 | 890.0 | 355.0 | 370.0 | 463.0 | 413.0 | 298.0 | 322.0 | 373.0 | 402.0 | 440.0 | 419.0 | 371.0 | 391.0 | 437.0 | 498.0 | 508.0 | 520.0 | 622.0 | 742.0 | 753.0 | 791.0 | 348.0 | 361.0 | 131.0 | 246.0 | 279.0 | 264.0 | 385.0 | 382.0 | 413.0 | NA | NA | 0.0 | NA | NA | NA |
| us-gaap:StockIssuedDuringPeriodValueNewIssues | NA | NA | NA | NA | 20.0 | 28.0 | 10.0 | NA | NA | NA | NA | NA | 76.0 | 65.0 | 10.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents us-gaap:AdditionalPaidInCapital | NA | NA | NA | NA | 20.0 | 28.0 | 10.0 | NA | NA | NA | NA | NA | 76.0 | 65.0 | 10.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | ▄▄ | 1.0 | 1.0 | NA | NA | NA | 1.0 | NA | NA | 1.0 | 0.0 | NA | NA | 1.0 | 1.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders | ▄ | 11.0 | NA | NA | NA | 6.0 | 3.0 | NA | NA | 4.0 | 30.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInOperatingActivities | █▆▃▄▇▄▃▄▇▄▃▄▆▄▃▅▆▄▃▄▇▄▄▄▆▂▃▂▄▃▂▂▄▁▂▂ | 288.0 | 194.0 | 47.0 | 104.0 | 257.0 | 100.0 | 84.0 | 103.0 | 224.0 | 89.0 | 61.0 | 102.0 | 215.0 | 116.0 | 65.0 | 142.0 | 203.0 | 110.0 | 61.0 | 121.0 | 241.0 | 96.0 | 102.0 | 104.0 | 181.0 | 10.0 | 78.0 | 29.0 | 121.0 | 57.0 | 16.0 | 38.0 | 122.0 | -29.0 | 10.0 | 38.0 | NA | NA | NA |
| us-gaap:NetCashProvidedByUsedInInvestingActivities | ▇▆▅▇▇█▇▆▇▆▇▇▇▆▇▇▇▇▇▇▆▇▇▆▇▅▄█▁▅█▇▇▆▆▆ | -10.0 | -106.0 | -314.0 | -42.0 | -60.0 | 57.0 | -17.0 | -168.0 | -89.0 | -185.0 | -26.0 | -10.0 | -9.0 | -122.0 | -44.0 | -79.0 | -61.0 | -80.0 | -63.0 | -19.0 | -100.0 | 16.0 | -58.0 | -222.0 | -59.0 | -348.0 | -489.0 | 53.0 | -917.0 | -331.0 | 127.0 | -95.0 | 18.0 | -129.0 | -182.0 | -143.0 | NA | NA | NA |
| us-gaap:NetCashProvidedByUsedInFinancingActivities | ▂▂▄▂▂▂▂▃▂▃▁▃▂▃▂▂▂▂▂▃▂▂▂▃▁▅▃▂█▂▄▂▂▃▃▃ | -193.0 | -49.0 | 233.0 | -134.0 | -76.0 | -121.0 | -104.0 | 85.0 | -34.0 | 94.0 | -320.0 | 102.0 | -86.0 | -2.0 | -60.0 | -77.0 | -118.0 | -113.0 | -107.0 | 15.0 | -30.0 | -99.0 | -79.0 | 81.0 | -278.0 | 505.0 | 119.0 | -63.0 | 1081.0 | -82.0 | 241.0 | -28.0 | -37.0 | 153.0 | 173.0 | 97.0 | NA | NA | NA |
| us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect | ▆▆▅▄▇▆▅▅▇▅▁█▇ | 85.0 | 39.0 | -34.0 | -72.0 | 121.0 | 36.0 | -37.0 | 20.0 | 101.0 | -2.0 | -285.0 | 194.0 | 120.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:DepreciationDepletionAndAmortization | ████▆▆▆▇▇▆▅▅▅▅▅▆▆▅▅▅▅▄▄▆▃▄▄▃▃▃▂▂▂▁▁▁▁▁ | 131.0 | 128.0 | 128.0 | 125.0 | 102.0 | 99.0 | 102.0 | 111.0 | 112.0 | 89.0 | 84.0 | 84.0 | 84.0 | 82.0 | 81.0 | 93.0 | 88.0 | 78.0 | 75.0 | 73.0 | 75.0 | 67.0 | 66.0 | 102.0 | 50.0 | 59.0 | 54.0 | 42.0 | 34.0 | 36.0 | 17.0 | 16.0 | 16.0 | 9.0 | 10.0 | 7.0 | 6.0 | 6.0 | NA |
| us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet | ▆▆▅▅▅▇▄▃▅▆▄▄▅▇▄▃▆▆▄▄▅▄▅▅▂█▅▄▄▆▆▅▁█▅▃ | 27.0 | 27.0 | 3.0 | 16.0 | 3.0 | 48.0 | -22.0 | -33.0 | 11.0 | 34.0 | -7.0 | -14.0 | 8.0 | 45.0 | -9.0 | -31.0 | 21.0 | 24.0 | -8.0 | -14.0 | 11.0 | -17.0 | 13.0 | 11.0 | -61.0 | 67.0 | 5.0 | -3.0 | -16.0 | 25.0 | 25.0 | 2.0 | -79.0 | 73.0 | 7.0 | -27.0 | NA | NA | NA |
| us-gaap:NetCashProvidedByUsedInOperatingActivities | █▆▃▄▇▄▃▄▇▄▃▄▆▄▃▅▆▄▃▄▇▄▄▄▆▂▃▂▄▃▂▂▄▁▂▂ | 288.0 | 194.0 | 47.0 | 104.0 | 257.0 | 100.0 | 84.0 | 103.0 | 224.0 | 89.0 | 61.0 | 102.0 | 215.0 | 116.0 | 65.0 | 142.0 | 203.0 | 110.0 | 61.0 | 121.0 | 241.0 | 96.0 | 102.0 | 104.0 | 181.0 | 10.0 | 78.0 | 29.0 | 121.0 | 57.0 | 16.0 | 38.0 | 122.0 | -29.0 | 10.0 | 38.0 | NA | NA | NA |
| us-gaap:NetIncomeLoss | ▆▇▄▁▇█▁▃▇▁▂ | 21.0 | 35.0 | 3.0 | -25.0 | 32.0 | 47.0 | -29.0 | -6.0 | 39.0 | -24.0 | -20.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 6.0 | 6.0 | NA | NA | 9.0 | 33.0 | NA | NA | NA | -1.0 | NA |
| us-gaap:ProfitLoss | ▆▆▃▃▆▇▂▃▆▄▃▂▇█▅▂▆▆▅▁▆▇▅▅▆▆▄▅▆▆▆▆▆▆▅▅▅▅▅ | 25.0 | 32.0 | -76.0 | -73.0 | 42.0 | 76.0 | -107.0 | -48.0 | 35.0 | -36.0 | -47.0 | -91.0 | 49.0 | 96.0 | 0.0 | -98.0 | 41.0 | 45.0 | -1.0 | -126.0 | 47.0 | 58.0 | 2.0 | 13.0 | 34.0 | 41.0 | -16.0 | -10.0 | 31.0 | 34.0 | 18.0 | 24.0 | 40.0 | 34.0 | 11.0 | 5.0 | 4.0 | -1.0 | 5.0 |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInInvestingActivities | ▇▆▅▇▇█▇▆▇▆▇▇▇▆▇▇▇▇▇▇▆▇▇▆▇▅▄█▁▅█▇▇▆▆▆ | -10.0 | -106.0 | -314.0 | -42.0 | -60.0 | 57.0 | -17.0 | -168.0 | -89.0 | -185.0 | -26.0 | -10.0 | -9.0 | -122.0 | -44.0 | -79.0 | -61.0 | -80.0 | -63.0 | -19.0 | -100.0 | 16.0 | -58.0 | -222.0 | -59.0 | -348.0 | -489.0 | 53.0 | -917.0 | -331.0 | 127.0 | -95.0 | 18.0 | -129.0 | -182.0 | -143.0 | NA | NA | NA |
| us-gaap:PaymentsToAcquirePropertyPlantAndEquipment | ▃▃▅▃▃▄▃▃▆▅▃▃▃▃▃▂▂▂▂▂▂▂▂▃▂▂▂▂▂▂▃▂▁▅█▆ | 31.0 | 14.0 | 79.0 | 29.0 | 12.0 | 43.0 | 40.0 | 28.0 | 104.0 | 80.0 | 16.0 | 21.0 | 17.0 | 27.0 | 18.0 | 8.0 | 10.0 | 9.0 | 4.0 | 4.0 | 5.0 | 4.0 | 7.0 | 13.0 | 8.0 | 5.0 | 3.0 | 5.0 | -1.0 | 10.0 | 19.0 | 6.0 | -35.0 | 88.0 | 179.0 | 107.0 | NA | NA | NA |
| us-gaap:PaymentsToAcquireProductiveAssets cwen:AssetAcquisition cwen:NedPowerMountStormLLC | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:PaymentsToAcquireProductiveAssets us-gaap:CounterpartyName,us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName,us-gaap:StatementEquityComponents cwen:CEG,cwen:PinnacleRepoweringPartnershipHoldCoLLC,us-gaap:NoncontrollingInterest | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInFinancingActivities | ▂▂▄▂▂▂▂▃▂▃▁▃▂▃▂▂▂▂▂▃▂▂▂▃▁▅▃▂█▂▄▂▂▃▃▃ | -193.0 | -49.0 | 233.0 | -134.0 | -76.0 | -121.0 | -104.0 | 85.0 | -34.0 | 94.0 | -320.0 | 102.0 | -86.0 | -2.0 | -60.0 | -77.0 | -118.0 | -113.0 | -107.0 | 15.0 | -30.0 | -99.0 | -79.0 | 81.0 | -278.0 | 505.0 | 119.0 | -63.0 | 1081.0 | -82.0 | 241.0 | -28.0 | -37.0 | 153.0 | 173.0 | 97.0 | NA | NA | NA |
| us-gaap:ProceedsFromIssuanceOfLongTermDebt | ▂▂█▄▅▃▂▆▂▅▂▅▂▃▂▂▂▂▂▂▅▂▂▃▂▄▃▂▅▂▄▂▁▃▄▂ | 21.0 | 12.0 | 1004.0 | 309.0 | 489.0 | 255.0 | 31.0 | 629.0 | 93.0 | 489.0 | 4.0 | 600.0 | 0.0 | 213.0 | 14.0 | 0.0 | 0.0 | 0.0 | 41.0 | 125.0 | 550.0 | 0.0 | 0.0 | 255.0 | 14.0 | 365.0 | 210.0 | 0.0 | 538.0 | 41.0 | 345.0 | 0.0 | -99.0 | 163.0 | 356.0 | 68.0 | NA | NA | NA |
| us-gaap:RepaymentsOfLongTermDebt | ▂▁█▄▅▁▄▇▁▃▃▄▁▂▁▁▁▁▁▁▁▁▁▁ | 142.0 | 71.0 | 957.0 | 473.0 | 507.0 | 110.0 | 437.0 | 784.0 | 84.0 | 312.0 | 304.0 | 425.0 | 100.0 | 206.0 | 79.0 | 108.0 | 82.0 | 67.0 | 75.0 | 60.0 | 82.0 | 55.0 | 67.0 | 55.0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
|---|
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2014-12-31 | 2013-06-30 | 2012-12-31 |
| Value | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 10.0 | 10.0 |
| Percentage of CommonStockValue | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-09-30 | 2015-06-30 |
| Value | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 49 | 35 | 35 | 49 | 49 | 35 | 35 | 49 | 49 | 35 | 35 | 35 |
| Percentage of WeightedAverageNumberOfDilutedSharesOutstanding | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-09-30 | 2015-06-30 |
| Value | 82 | 82 | 81 | 80 | 75 | 75 | 73 | 73 | 73 | 69 | 78 | 65 | 65 | 75 | 74 | 63 | 63 | 73 | 73 | 63 | 63 | 35 |
| Percentage of WeightedAverageNumberOfDilutedSharesOutstanding | 234.3 | 234.3 | 231.4 | 228.6 | 214.3 | 214.3 | 208.6 | 208.6 | 208.6 | 197.1 | 159.2 | 185.7 | 185.7 | 153.1 | 151.0 | 180.0 | 180.0 | 149.0 | 149.0 | 180.0 | 180.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 |
| Value | 82 | 82 | 81 | 80 | 75 | 73 | 73 | 73 | 73 | 69 | 67 | 65 | 65 | 64 | 63 | 63 | 63 | 63 | 63 | 63 | 63 | 63 | 35 | 35 |
| Percentage of WeightedAverageNumberOfSharesOutstandingBasic | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-03-31 | 2017-03-31 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-09-30 | 2014-06-30 |
| Value | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 35 | 31 | 23 |
| Percentage of WeightedAverageNumberOfShareOutstandingBasicAndDiluted | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-06-30 | 2019-03-31 | 2018-03-31 | 2017-03-31 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-09-30 | 2014-06-30 |
| Value | 82 | 81 | 81 | 80 | 79 | 73 | 73 | 65 | 63 | 63 | 63 | 63 | 35 | 35 | 31 | 23 |
| Percentage of WeightedAverageNumberOfShareOutstandingBasicAndDiluted | 234.3 | 231.4 | 231.4 | 228.6 | 225.7 | 208.6 | 208.6 | 185.7 | 180.0 | 180.0 | 180.0 | 180.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2017-09-30 | 2017-06-30 | 2016-09-30 | 2016-06-30 | 2015-09-30 | 2015-06-30 |
| Value | 0.18 | 0.3 | 0.27 | 0.41 | 0.36 | -0.22 | 0.2 | 0.77 | 0.3 | 0.29 | 0.34 | 0.33 | 0.18 | 0.15 |
| Percentage of EarningsPerShareBasic | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2015-12-31 | 2015-09-30 | 2015-06-30 |
| Value | 0.18 | 0.3 | 0.27 | 0.41 | 0.36 | -0.22 | 0.2 | 0.77 | 0.16 | 0.3 | 0.29 | -0.03 | -0.14 | 0.34 | 0.33 | 0.12 | 0.18 | 0.15 |
| Percentage of EarningsPerShareBasic | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-09-30 | 2015-06-30 |
| Value | 0.18 | 0.3 | 0.27 | 0.41 | 0.36 | -0.22 | -0.63 | 0.2 | 0.61 | 0.16 | -0.71 | 0.27 | 0.26 | -0.03 | -0.14 | 0.3 | 0.29 | 0.05 | 0.18 | 0.15 |
| Percentage of EarningsPerShareDiluted | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-09-30 | 2015-06-30 |
| Value | 0.18 | 0.3 | 0.27 | 0.41 | 0.36 | -0.22 | -0.63 | 0.2 | 0.7 | 0.16 | -0.71 | 0.29 | 0.28 | -0.03 | -0.14 | 0.32 | 0.31 | 0.05 | 0.18 | 0.15 |
| Percentage of EarningsPerShareDiluted | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 114.8 | 100.0 | 100.0 | 107.4 | 107.7 | 100.0 | 100.0 | 106.7 | 106.9 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-03-31 | 2019-03-31 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 |
| Value | 0.03 | -0.26 | -0.18 | -0.15 | -0.03 | 0.2 | 0.18 | 0.18 | 0.39 |
| Percentage of EarningsPerShareBasicAndDiluted | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-03-31 | 2017-06-30 | 2017-03-31 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 |
| Value | 0.03 | -0.21 | 0.27 | 0.41 | -0.26 | -0.06 | 0.37 | -0.22 | -0.18 | 0.16 | 0.29 | -0.03 | 0.33 | 0.05 | 0.12 | 0.18 | 0.15 | -0.07 | -0.01 | 0.1 | 0.13 |
| Percentage of EarningsPerShareBasicAndDiluted | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 46.7 | 33.3 | 50.0 | 0.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-03-31 | 2017-06-30 | 2017-03-31 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 |
| Value | 0.03 | -0.2 | 0.27 | 0.41 | -0.26 | -0.06 | -0.36 | -0.22 | -0.18 | 0.16 | 0.29 | -0.03 | 0.33 | 0.05 | 0.12 | 0.18 | 0.15 | -0.07 | -0.01 | 0.1 | 0.13 |
| Percentage of EarningsPerShareBasicAndDiluted | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 46.7 | 33.3 | 50.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 |
| Value | 22 | 35 | 7.0 | -24.0 | 36 | 49 | -35.0 | -4.0 | 38 | -21.0 | -21.0 | -72.0 | 24 | 82 | 24 | -71.0 | 30 | 25 | 0.0 | 7.0 | 32 | 29 | -12.0 | 16 | 1.0 | 16 | -18.0 | -2.0 | 8.0 | 2.0 | -3.0 |
| Percentage of ComprehensiveIncomeNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.3 | 9.2 | 3.0 | -8.6 | 10.8 | 14.9 | -63.6 | -1.7 | 59.4 | -36.8 | -38.2 | -31.4 | 38.1 | 141.4 | 39.3 | -30.7 | 11.3 | 8.8 | 0.0 | 3.0 | 11.8 | 11.2 | -5.5 | 7.7 | 0.5 | 7.4 | -10.0 | -1.4 | 5.0 | 1.5 | -2.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 |
| Value | 6.0 | -3.0 | -72.0 | -48.0 | 14 | 31 | -84.0 | -39.0 | -4.0 | -10.0 | -28.0 | -27.0 | 31 | 21 | -11.0 | -24.0 | 17 | 14 | -7.0 | -84.0 | 30 | 13 | -27.0 | 17 | 4.0 | 46 | -15.0 | -20.0 | 30 | 11 | 9.0 | 49 | 28 | 59 |
| Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | -0.8 | -30.4 | -17.1 | 4.2 | 9.4 | -152.7 | -16.6 | -6.2 | -17.5 | -50.9 | -11.8 | 49.2 | 36.2 | -18.0 | -10.4 | 6.4 | 4.9 | -3.2 | -36.2 | 11.0 | 5.0 | -12.3 | 8.1 | 1.9 | 21.2 | -8.3 | -13.5 | 18.6 | 8.2 | 8.2 | 57.0 | 29.5 | 74.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 28 | 32 | -65.0 | -72.0 | 50 | 80 | -119.0 | -43.0 | 34 | -31.0 | -49.0 | -99.0 | 55 | 103 | 17 | -105.0 | 48 | 39 | 5.0 | -77.0 | 68 | 42 | -39.0 | 13 | 5.0 | 62 | -33.0 | -22.0 | 38 | 22 | 12 | 32 | 37 | 60 | 12 | 6.0 | 1.0 |
| Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 8.0 | 8.4 | -27.4 | -25.7 | 15.1 | 24.3 | -216.4 | -18.3 | 53.1 | -54.4 | -89.1 | -43.2 | 87.3 | 177.6 | 27.9 | -45.5 | 18.1 | 13.7 | 2.3 | -33.2 | 25.0 | 16.3 | -17.7 | 6.2 | 2.4 | 28.6 | -18.3 | -14.9 | 23.6 | 16.4 | 10.9 | 37.2 | 38.9 | 75.9 | 22.6 | 14.3 | 2.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 117 | 107 | 110 | 91 | 95 | 87 | 93 | 93 | 86 | 79 | 84 | 85 | 84 | 74 | 89 | 87 | 78 | 77 | 84 | 68 | 76 | 75 | 83 | 101 | 69 | 67 | 75 | 57 | 52 | 45 | 53 | 35 | 33 | 32 | 29 | 31 | 28 |
| Percentage of CostOfRevenue | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 33.3 | 28.2 | 46.4 | 32.5 | 28.6 | 26.4 | 169.1 | 39.6 | 134.4 | 138.6 | 152.7 | 37.1 | 133.3 | 127.6 | 145.9 | 37.7 | 29.4 | 27.1 | 38.5 | 29.3 | 27.9 | 29.1 | 37.7 | 48.3 | 33.0 | 30.9 | 41.7 | 38.5 | 32.3 | 33.6 | 48.2 | 40.7 | 34.7 | 40.5 | 54.7 | 73.8 | 59.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 0.0 | -1.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of CostOfRevenue | 0.0 | -0.9 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | -0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 20 | 23 | 27 | 23 | 21 | 22 | 24 | 17 | 14 | 13 | 17 | 18 | 12 |
| Percentage of CostOfRevenue | 17.1 | 21.5 | 24.5 | 25.3 | 22.1 | 25.3 | 25.8 | 18.3 | 16.3 | 16.5 | 20.2 | 21.2 | 14.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 5.7 | 6.1 | 11.4 | 8.2 | 6.3 | 6.7 | 43.6 | 7.2 | 21.9 | 22.8 | 30.9 | 7.9 | 19.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 60 | 54 | 52 | 39 | 33 | 39 | 36 | 41 | 36 | 35 | 33 | 37 | 39 |
| Percentage of CostOfRevenue | 51.3 | 50.5 | 47.3 | 42.9 | 34.7 | 44.8 | 38.7 | 44.1 | 41.9 | 44.3 | 39.3 | 43.5 | 46.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 17.1 | 14.2 | 21.9 | 13.9 | 9.9 | 11.9 | 65.5 | 17.4 | 56.2 | 61.4 | 60.0 | 16.2 | 61.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 125.0 | 98.2 | -520.0 | 0.0 | 173.7 | 216.7 | 514.3 | 0.0 | 400.0 | 318.2 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 37 | 31 | 31 | 31 | 41 | 26 | 33 | 35 | 36 | 30 | 33 | 30 | 33 |
| Percentage of CostOfRevenue | 31.6 | 29.0 | 28.2 | 34.1 | 43.2 | 29.9 | 35.5 | 37.6 | 41.9 | 38.0 | 39.3 | 35.3 | 39.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 10.5 | 8.2 | 13.1 | 11.1 | 12.3 | 7.9 | 60.0 | 14.9 | 56.2 | 52.6 | 60.0 | 13.1 | 52.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 68.5 | 62.0 | 63.3 | 0.0 | 68.3 | 61.9 | 68.8 | 0.0 | 65.5 | 65.2 | 66.0 | 0.0 | 62.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 262 | 247 | 251 | 252 | 209 | 199 | 206 | 229 | 206 | 197 | 176 | 175 | 192 | 163 | 176 | 230 | 170 | 162 | 164 | 331 | 155 | 145 | 152 | 207 | 123 | 130 | 132 | 102 | 91 | 83 | 72 | 53 | 50 | 44 | 41 | 39 | 36 |
| Percentage of CostsAndExpenses | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 74.6 | 65.0 | 105.9 | 90.0 | 63.0 | 60.5 | 374.5 | 97.4 | 321.9 | 345.6 | 320.0 | 76.4 | 304.8 | 281.0 | 288.5 | 99.6 | 64.2 | 57.0 | 75.2 | 142.7 | 57.0 | 56.2 | 69.1 | 99.0 | 58.9 | 59.9 | 73.3 | 68.9 | 56.5 | 61.9 | 65.5 | 61.6 | 52.6 | 55.7 | 77.4 | 92.9 | 76.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2014-12-31 | 2014-09-30 | 2014-06-30 |
| Value | 0.0 | 0.0 | -42.0 | -15.0 | -6.0 | 0.0 | -3.0 | -15.0 | 0.0 | -1.0 | 0.0 | -7.0 | 0.0 | 0.0 | 0.0 | -1.0 | 0.0 | 0.0 | -2.0 | 0.0 | 0.0 | 0.0 | 0.0 | -2.0 | -7.0 | 0.0 | 0.0 | 0.0 |
| Percentage of GainsLossesOnExtinguishmentOfDebt | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.0 | -17.7 | -5.4 | -1.8 | 0.0 | -5.5 | -6.4 | 0.0 | -1.8 | 0.0 | -3.1 | 0.0 | 0.0 | 0.0 | -0.4 | 0.0 | 0.0 | -0.9 | 0.0 | 0.0 | 0.0 | 0.0 | -1.0 | -3.2 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 |
| Value | 0.0 | 0.0 | -41.0 | 0.0 | 0.0 | 0.0 | -3.0 | -15.0 | 0.0 | 0.0 |
| Percentage of GainsLossesOnExtinguishmentOfDebt | 0.0 | 0.0 | 97.6 | -0.0 | -0.0 | 0.0 | 100.0 | 100.0 | 0.0 | -0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.0 | -17.3 | 0.0 | 0.0 | 0.0 | -5.5 | -6.4 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 |
| Value | 0.0 | 0.0 | -1.0 | -15.0 | -6.0 | 0.0 | 0.0 | 0.0 | 0.0 | -1.0 |
| Percentage of GainsLossesOnExtinguishmentOfDebt | 0.0 | 0.0 | 2.4 | 100.0 | 100.0 | 0.0 | -0.0 | -0.0 | 0.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.0 | -0.4 | -5.4 | -1.8 | 0.0 | 0.0 | 0.0 | 0.0 | -1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 0.0 | 0.0 | 10.0 | 0.0 | -31.6 | 0.0 | 0.0 | 0.0 | 0.0 | -9.1 |
| Period End | 2021-09-30 |
| Value | 0.0 |
| Percentage of GainsLossesOnExtinguishmentOfDebt | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:A5.75SeniorNotesdue2025 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 |
| Value | 10.0 | 10.0 | 10.0 | 4.0 | 9.0 | 12 | 9.0 | 9.0 | 7.0 | 7.0 | 6.0 | 3.0 | 6.0 | 6.0 | 5.0 | 5.0 | 4.0 | 6.0 | 4.0 | 6.0 | 4.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 1.0 | 3.0 | 2.0 | 2.0 | 2.0 | 1.0 | 2.0 | 2.0 |
| Percentage of GeneralAndAdministrativeExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 2.8 | 2.6 | 4.2 | 1.4 | 2.7 | 3.6 | 16.4 | 3.8 | 10.9 | 12.3 | 10.9 | 1.3 | 9.5 | 10.3 | 8.2 | 2.2 | 1.5 | 2.1 | 1.8 | 2.6 | 1.5 | 1.2 | 1.4 | 1.4 | 1.4 | 1.4 | 1.7 | 0.7 | 1.9 | 1.5 | 1.8 | 2.3 | 1.1 | 2.5 | 3.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 9.0 | 9.0 | 9.0 | 6.0 | 8.0 | 9.0 | 8.0 | 8.0 | 5.0 | 7.0 | 5.0 | 2.0 | 6.0 |
| Percentage of GeneralAndAdministrativeExpense | 90.0 | 90.0 | 90.0 | 150.0 | 88.9 | 75.0 | 88.9 | 88.9 | 71.4 | 100.0 | 83.3 | 66.7 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 2.6 | 2.4 | 3.8 | 2.1 | 2.4 | 2.7 | 14.5 | 3.4 | 7.8 | 12.3 | 9.1 | 0.9 | 9.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 0.0 | 1.0 | 0.0 | 1.0 | 0.0 | 0.0 | 1.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of GeneralAndAdministrativeExpense | 0.0 | 10.0 | 0.0 | 8.3 | 0.0 | 0.0 | 14.3 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.3 | 0.0 | 0.3 | 0.0 | 0.0 | 1.6 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 0.0 | 1.8 | 0.0 | 5.6 | 0.0 | 0.0 | 11.1 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 1.0 | 0.0 | 1.0 | -1.0 | 1.0 | 2.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 0.0 |
| Percentage of GeneralAndAdministrativeExpense | 10.0 | 0.0 | 10.0 | -25.0 | 11.1 | 16.7 | 11.1 | 11.1 | 14.3 | 0.0 | 16.7 | 33.3 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 0.0 | 0.4 | -0.4 | 0.3 | 0.6 | 1.8 | 0.4 | 1.6 | 0.0 | 1.8 | 0.4 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 1.9 | 0.0 | 2.0 | 0.0 | 1.7 | 4.8 | 2.1 | 0.0 | 1.8 | 0.0 | 2.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 1.0 | 1.0 | 1.0 | 0.0 | 0.6 | 0.6 | 0.6 |
| Percentage of GeneralAndAdministrativeExpense | 10.0 | 10.0 | 10.0 | 0.0 | 6.7 | 5.0 | 6.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 0.3 | 0.4 | 0.0 | 0.2 | 0.2 | 1.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:CEG | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 |
| Value | 26 | 39 | -96.0 | -78.0 | 51 | 102 | -129.0 | -42.0 | 24 | -32.0 | -54.0 | -46.0 | 60 | 103 | -1.0 | -51.0 | 49 | 53 | -2.0 | -152.0 | 60 | 70 | 2.0 | 0.0 | 42 | 45 | -20.0 | -21.0 | 41 | 36 | 21 | 27 | 45 | 34 | 11 | 5.0 | 12 | -2.0 |
| Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 7.4 | 10.3 | -40.5 | -27.9 | 15.4 | 31.0 | -234.5 | -17.9 | 37.5 | -56.1 | -98.2 | -20.1 | 95.2 | 177.6 | -1.6 | -22.1 | 18.5 | 18.7 | -0.9 | -65.5 | 22.1 | 27.1 | 0.9 | 0.0 | 20.1 | 20.7 | -11.1 | -14.2 | 25.5 | 26.9 | 19.1 | 31.4 | 47.4 | 43.0 | 20.8 | 11.9 | 25.5 | -4.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -36.0 | -34.0 | -77.0 | -37.0 | -32.0 | 16 | -35.0 | -46.0 | -28.0 | -29.0 | -27.0 | -34.0 | -44.0 |
| Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | -138.5 | -87.2 | 80.2 | 47.4 | -62.7 | 15.7 | 27.1 | 109.5 | -116.7 | 90.6 | 50.0 | 73.9 | -73.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -10.3 | -8.9 | -32.5 | -13.2 | -9.6 | 4.9 | -63.6 | -19.6 | -43.8 | -50.9 | -49.1 | -14.8 | -69.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 52 | 40 | 33 | 43 | 48 | 31 | 18 | 38 | 41 | 32 | 24 | 28 | 39 |
| Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 200.0 | 102.6 | -34.4 | -55.1 | 94.1 | 30.4 | -14.0 | -90.5 | 170.8 | -100.0 | -44.4 | -60.9 | 65.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 14.8 | 10.5 | 13.9 | 15.4 | 14.5 | 9.4 | 32.7 | 16.2 | 64.1 | 56.1 | 43.6 | 12.2 | 61.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 6.0 | 27 | -56.0 | -83.0 | 34 | 54 | -114.0 | -34.0 | 6.0 | -20.0 | -56.0 | -45.0 | 55 |
| Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 23.1 | 69.2 | 58.3 | 106.4 | 66.7 | 52.9 | 88.4 | 81.0 | 25.0 | 62.5 | 103.7 | 97.8 | 91.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | 7.1 | -23.6 | -29.6 | 10.2 | 16.4 | -207.3 | -14.5 | 9.4 | -35.1 | -101.8 | -19.7 | 87.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 12.5 | 49.1 | 560.0 | 0.0 | 178.9 | 300.0 | -1628.6 | 0.0 | 66.7 | -181.8 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 4.0 | 6.0 | 4.0 | -1.0 | 1.0 | 1.0 | 2.0 | 0.0 | 5.0 | -15.0 | 5.0 | 5.0 | 10.0 |
| Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 15.4 | 15.4 | -4.2 | 1.3 | 2.0 | 1.0 | -1.6 | -0.0 | 20.8 | 46.9 | -9.3 | -10.9 | 16.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.1 | 1.6 | 1.7 | -0.4 | 0.3 | 0.3 | 3.6 | 0.0 | 7.8 | -26.3 | 9.1 | 2.2 | 15.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 7.4 | 12.0 | 8.2 | 0.0 | 1.7 | 2.4 | 4.2 | 0.0 | 9.1 | -32.6 | 10.0 | 0.0 | 18.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 1.0 | 7.0 | -20.0 | -5.0 | 9.0 | 26 | -22.0 | 6.0 | -11.0 | 4.0 | -7.0 | 45 | 11 | 7.0 | -1.0 | 57 | 8.0 | 8.0 | -1.0 | -26.0 | 13 | 12 | 0.0 | 4.0 | 8.0 | 4.0 | -4.0 | -11.0 | 10.0 | 2.0 | 3.0 | 3.0 | 5.0 | 0.0 | 0.0 | 0.0 | 8.0 |
| Percentage of IncomeTaxExpenseBenefit | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 1.8 | -8.4 | -1.8 | 2.7 | 7.9 | -40.0 | 2.6 | -17.2 | 7.0 | -12.7 | 19.7 | 17.5 | 12.1 | -1.6 | 24.7 | 3.0 | 2.8 | -0.5 | -11.2 | 4.8 | 4.7 | 0.0 | 1.9 | 3.8 | 1.8 | -2.2 | -7.4 | 6.2 | 1.5 | 2.7 | 3.5 | 5.3 | 0.0 | 0.0 | 0.0 | 17.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 1.0 | 7.0 | -20.0 | -5.0 | 9.0 | 26 | -22.0 | 6.0 | -11.0 | 4.0 | -7.0 | 45 | 11 |
| Percentage of IncomeTaxExpenseBenefit | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 1.8 | -8.4 | -1.8 | 2.7 | 7.9 | -40.0 | 2.6 | -17.2 | 7.0 | -12.7 | 19.7 | 17.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 84 | 103 | 45 | 70 | 85 | 93 | 167 | 67 | 106 | 130 | 101 | 106 | 74 | 71 | 55 | 69 | 75 | 86 | 76 | 61 | 71 | 62 | 68 | 62 | 62 | 44 | 70 | 69 | 41 | 29 | 19 | 11 | 13 | 6.0 | 5.0 | 3.0 | 5.0 |
| Percentage of InterestExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 23.9 | 27.1 | 19.0 | 25.0 | 25.6 | 28.3 | 303.6 | 28.5 | 165.6 | 228.1 | 183.6 | 46.3 | 117.5 | 122.4 | 90.2 | 29.9 | 28.3 | 30.3 | 34.9 | 26.3 | 26.1 | 24.0 | 30.9 | 29.7 | 29.7 | 20.3 | 38.9 | 46.6 | 25.5 | 21.6 | 17.3 | 12.8 | 13.7 | 7.6 | 9.4 | 7.1 | 10.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 24 | 25 | 25 | 26 | 23 | 24 | 23 | 22 | 23 | 21 | 22 | 25 | 21 |
| Percentage of InterestExpense | 28.6 | 24.3 | 55.6 | 37.1 | 27.1 | 25.8 | 13.8 | 32.8 | 21.7 | 16.2 | 21.8 | 23.6 | 28.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.8 | 6.6 | 10.5 | 9.3 | 6.9 | 7.3 | 41.8 | 9.4 | 35.9 | 36.8 | 40.0 | 10.9 | 33.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 14 | 16 | 11 | 15 | 17 | 22 | 30 | 14 | 13 | 16 | 16 | 18 | 13 |
| Percentage of InterestExpense | 16.7 | 15.5 | 24.4 | 21.4 | 20.0 | 23.7 | 18.0 | 20.9 | 12.3 | 12.3 | 15.8 | 17.0 | 17.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.0 | 4.2 | 4.6 | 5.4 | 5.1 | 6.7 | 54.5 | 6.0 | 20.3 | 28.1 | 29.1 | 7.9 | 20.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 41 | 58 | 4.0 | 26 | 39 | 42 | 109 | 26 | 65 | 89 | 59 | 59 | 36 |
| Percentage of InterestExpense | 48.8 | 56.3 | 8.9 | 37.1 | 45.9 | 45.2 | 65.3 | 38.8 | 61.3 | 68.5 | 58.4 | 55.7 | 48.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 11.7 | 15.3 | 1.7 | 9.3 | 11.7 | 12.8 | 198.2 | 11.1 | 101.6 | 156.1 | 107.3 | 25.8 | 57.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 85.4 | 105.5 | -40.0 | 0.0 | 205.3 | 233.3 | 1557.1 | 0.0 | 722.2 | 809.1 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 5.0 | 4.0 | 5.0 | 3.0 | 6.0 | 5.0 | 5.0 | 5.0 | 5.0 | 4.0 | 4.0 | 4.0 | 4.0 |
| Percentage of InterestExpense | 6.0 | 3.9 | 11.1 | 4.3 | 7.1 | 5.4 | 3.0 | 7.5 | 4.7 | 3.1 | 4.0 | 3.8 | 5.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.4 | 1.1 | 2.1 | 1.1 | 1.8 | 1.5 | 9.1 | 2.1 | 7.8 | 7.0 | 7.3 | 1.7 | 6.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 9.3 | 8.0 | 10.2 | 0.0 | 10.0 | 11.9 | 10.4 | 0.0 | 9.1 | 8.7 | 8.0 | 0.0 | 7.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2014-09-30 | 2014-06-30 | 2013-09-30 | 2013-06-30 | 2012-06-30 |
| Value | 21 | 35 | 3.0 | -25.0 | 32 | 47 | -29.0 | -6.0 | 39 | -24.0 | -20.0 | 6.0 | 6.0 | 9.0 | 33 | -1.0 |
| Percentage of NetIncomeLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.0 | 9.2 | 1.3 | -8.9 | 9.6 | 14.3 | -52.7 | -2.6 | 60.9 | -42.1 | -36.4 | 3.7 | 4.5 | 9.5 | 41.8 | -2.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 6.0 | 10.0 | 1.0 | 9.0 | 14 | -9.0 | 12 | -8.0 | -6.0 |
| Percentage of NetIncomeLoss | 28.6 | 28.6 | 33.3 | 28.1 | 29.8 | 31.0 | 30.8 | 33.3 | 30.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | 2.6 | 0.4 | 2.7 | 4.3 | -16.4 | 18.8 | -14.0 | -10.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 15 | 25 | 2.0 | 22 | 33 | -20.0 | 27 | -16.0 | -14.0 |
| Percentage of NetIncomeLoss | 71.4 | 71.4 | 66.7 | 68.8 | 70.2 | 69.0 | 69.2 | 66.7 | 70.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.3 | 6.6 | 0.8 | 6.6 | 10.0 | -36.4 | 42.2 | -28.1 | -25.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassC | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 |
| Value | 4.0 | -3.0 | -79.0 | -48.0 | 10.0 | 29 | -78.0 | -42.0 | -4.0 | -12.0 | -27.0 | -23.0 | 28 | 17 | -20.0 | -28.0 | 11 | 17 | -10.0 | -113.0 | 8.0 | 26 | -3.0 | 5.0 | 17 | 31 | -11.0 | 6.0 | 25 | 19 |
| Percentage of NetIncomeLossAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.1 | -0.8 | -33.3 | -17.1 | 3.0 | 8.8 | -141.8 | -17.9 | -6.2 | -21.1 | -49.1 | -10.0 | 44.4 | 29.3 | -32.8 | -12.1 | 4.2 | 6.0 | -4.6 | -48.7 | 2.9 | 10.1 | -1.4 | 2.4 | 8.1 | 14.3 | -6.1 | 4.1 | 15.5 | 14.2 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -1.0 | -6.0 | -2.0 |
| Percentage of NetIncomeLossAttributableToNoncontrollingInterest | -10.0 | -20.7 | 2.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.3 | -1.8 | -3.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:RepoweringPartnershipIILLC cwen:ElbowCreekTEHoldco | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0.0 | -8.0 | -28.0 |
| Percentage of NetIncomeLossAttributableToNoncontrollingInterest | 0.0 | -27.6 | 35.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | -2.4 | -50.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:RepoweringPartnershipIILLC cwen:WildoradoTEHoldco | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 |
| Value | -25.0 | 32 | 47 | -29.0 | -6.0 | 39 | -24.0 | -20.0 | -68.0 | 21 | 79 | 16 | -70.0 | 29 | 28 | -3.0 | -13.0 | 33 | 32 | 5.0 | 11 | 17 | 10.0 | -5.0 | 0.0 | 6.0 | 6.0 | 4.0 | 4.0 | 9.0 |
| Percentage of NetIncomeLossAvailableToCommonStockholdersBasic | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -8.9 | 9.6 | 14.3 | -52.7 | -2.6 | 60.9 | -42.1 | -36.4 | -29.7 | 33.3 | 136.2 | 26.2 | -30.3 | 10.9 | 9.9 | -1.4 | -5.6 | 12.1 | 12.4 | 2.3 | 5.3 | 8.1 | 4.6 | -2.8 | 0.0 | 3.7 | 4.5 | 3.6 | 4.7 | 9.5 |
| Period End | 2020-09-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2017-09-30 | 2017-06-30 | 2016-09-30 | 2016-06-30 | 2015-09-30 | 2015-06-30 |
| Value | 9.0 | 12 | -8.0 | 7.0 | 30 | 13 | 13 | 15 | 14 | 6.0 | 5.0 |
| Percentage of NetIncomeLossAvailableToCommonStockholdersDiluted | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 2.7 | 18.8 | -14.0 | 11.1 | 51.7 | 4.9 | 4.6 | 5.5 | 5.4 | 2.9 | 2.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2017-09-30 | 2017-06-30 | 2016-09-30 | 2016-06-30 | 2015-09-30 | 2015-06-30 |
| Value | 22 | 27 | -16.0 | 14 | 55 | 21 | 21 | 24 | 23 | 11 | 5.0 |
| Percentage of NetIncomeLossAvailableToCommonStockholdersDiluted | 244.4 | 225.0 | 200.0 | 200.0 | 183.3 | 161.5 | 161.5 | 160.0 | 164.3 | 183.3 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.6 | 42.2 | -28.1 | 22.2 | 94.8 | 7.9 | 7.4 | 8.8 | 8.9 | 5.3 | 2.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassC | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | -63.0 | -94.0 | -82.0 | -106.0 | -72.0 | -28.0 | -181.0 | -48.0 | -66.0 | -119.0 | -95.0 | -100.0 | -40.0 | -41.0 | -50.0 | -63.0 | -46.0 | -69.0 | -56.0 | -53.0 | -57.0 | -43.0 | -66.0 | -56.0 | -44.0 | -42.0 | -68.0 | -67.0 | -29.0 | -15.0 | -17.0 | -6.0 | 0.0 | -3.0 | -1.0 | 2.0 | 1.0 |
| Percentage of NonoperatingIncomeExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -17.9 | -24.7 | -34.6 | -37.9 | -21.7 | -8.5 | -329.1 | -20.4 | -103.1 | -208.8 | -172.7 | -43.7 | -63.5 | -70.7 | -82.0 | -27.3 | -17.4 | -24.3 | -25.7 | -22.8 | -21.0 | -16.7 | -30.0 | -26.8 | -21.1 | -19.4 | -37.8 | -45.3 | -18.0 | -11.2 | -15.5 | -7.0 | 0.0 | -3.8 | -1.9 | 4.8 | 2.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
| Value | 89 | 133 | -14.0 | 28 | 123 | 130 | 52 | 6.0 | 90 | 87 | 41 | 54 | 100 | 144 | 49 | 19 | 95 | 122 | 54 | -99.0 | 117 | 113 | 68 | 66 | 86 | 87 | 48 | 46 | 70 | 51 | 38 | 33 | 45 | 38 | 12 | 3.0 | 11 | 8.0 | 9.0 |
| Percentage of OperatingIncomeLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 25.4 | 35.0 | -5.9 | 10.0 | 37.0 | 39.5 | 94.5 | 2.6 | 140.6 | 152.6 | 74.5 | 23.6 | 158.7 | 248.3 | 80.3 | 8.2 | 35.8 | 43.0 | 24.8 | -42.7 | 43.0 | 43.8 | 30.9 | 31.6 | 41.1 | 40.1 | 26.7 | 31.1 | 43.5 | 38.1 | 34.5 | 38.4 | 47.4 | 48.1 | 22.6 | 7.1 | 23.4 | 19.0 | 20.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -12.0 | -9.0 | -11.0 | -11.0 | -9.0 | -9.0 | -9.0 | -9.0 | -5.0 | -8.0 | -6.0 | -3.0 | -24.0 |
| Percentage of OperatingIncomeLoss | -13.5 | -6.8 | 78.6 | -39.3 | -7.3 | -6.9 | -17.3 | -150.0 | -5.6 | -9.2 | -14.6 | -5.6 | -24.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -3.4 | -2.4 | -4.6 | -3.9 | -2.7 | -2.7 | -16.4 | -3.8 | -7.8 | -14.0 | -10.9 | -1.3 | -38.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 64 | 55 | 41 | 56 | 61 | 52 | 46 | 49 | 51 | 46 | 37 | 43 | 49 |
| Percentage of OperatingIncomeLoss | 71.9 | 41.4 | -292.9 | 200.0 | 49.6 | 40.0 | 88.5 | 816.7 | 56.7 | 52.9 | 90.2 | 79.6 | 49.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 18.2 | 14.5 | 17.3 | 20.0 | 18.4 | 15.8 | 83.6 | 20.9 | 79.7 | 80.7 | 67.3 | 18.8 | 77.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 29 | 78 | -53.0 | -19.0 | 63 | 81 | 9.0 | -39.0 | 34 | 60 | 1.0 | 6.0 | 61 |
| Percentage of OperatingIncomeLoss | 32.6 | 58.6 | 378.6 | -67.9 | 51.2 | 62.3 | 17.3 | -650.0 | 37.8 | 69.0 | 2.4 | 11.1 | 61.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 8.3 | 20.5 | -22.4 | -6.8 | 19.0 | 24.6 | 16.4 | -16.6 | 53.1 | 105.3 | 1.8 | 2.6 | 96.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 60.4 | 141.8 | 530.0 | 0.0 | 331.6 | 450.0 | 128.6 | 0.0 | 377.8 | 545.5 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 8.0 | 9.0 | 9.0 | 2.0 | 8.0 | 6.0 | 6.0 | 5.0 | 10.0 | -11.0 | 9.0 | 8.0 | 14 |
| Percentage of OperatingIncomeLoss | 9.0 | 6.8 | -64.3 | 7.1 | 6.5 | 4.6 | 11.5 | 83.3 | 11.1 | -12.6 | 22.0 | 14.8 | 14.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 2.3 | 2.4 | 3.8 | 0.7 | 2.4 | 1.8 | 10.9 | 2.1 | 15.6 | -19.3 | 16.4 | 3.5 | 22.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 14.8 | 18.0 | 18.4 | 0.0 | 13.3 | 14.3 | 12.5 | 0.0 | 18.2 | -23.9 | 18.0 | 0.0 | 26.4 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 0.0 | 4.0 | 2.0 | 6.0 | 4.0 | 1.0 |
| Percentage of OperatingIncomeLoss | 0.0 | 3.1 | 3.8 | 6.7 | 4.6 | 2.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 1.2 | 3.6 | 9.4 | 7.0 | 1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:DGPVHoldco3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 3.0 | 0.0 | 11 | 8.0 | 4.0 | -12.0 | 5.0 | -1.0 | 5.0 | -2.0 |
| Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | 0.0 | 4.6 | 2.4 | 1.2 | -21.8 | 2.1 | -1.6 | 8.8 | -3.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 3.0 | 0.0 | 11 | 8.0 | 4.0 | -12.0 | 5.0 | -1.0 | 5.0 | -2.0 | -8.0 | 6.0 | 7.0 | 17 | 3.0 | 7.0 | -6.0 | 6.0 | 49 | 21 | -16.0 | -41.0 | 17 | -29.0 | 21 | -17.0 | -12.0 | 7.0 | -12.0 | -6.0 | 8.0 | -3.0 | 25 | 1.0 | 1.0 | -3.0 |
| Percentage of OtherComprehensiveIncomeLossNetOfTax | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | 0.0 | 4.6 | 2.4 | 1.2 | -21.8 | 2.1 | -1.6 | 8.8 | -3.6 | -3.5 | 9.5 | 12.1 | 27.9 | 1.3 | 2.6 | -2.1 | 2.8 | 21.1 | 7.7 | -6.2 | -18.6 | 8.1 | -13.9 | 9.7 | -9.4 | -8.1 | 4.3 | -9.0 | -5.5 | 9.3 | -3.2 | 31.6 | 1.9 | 2.4 | -6.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2018-06-30 |
| Value | 0.0 | -2.0 | 9.0 | -2.0 | 6.0 | 3.0 | -14.0 | 4.0 | 1.0 | -9.0 | 5.0 |
| Percentage of OtherComprehensiveIncomeLossNetOfTax | 0.0 | 0.0 | 81.8 | 0.0 | 75.0 | 75.0 | 116.7 | 80.0 | -100.0 | -180.0 | 71.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | -0.5 | 3.8 | -0.7 | 1.8 | 0.9 | -25.5 | 1.7 | 1.6 | -15.8 | 8.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedNetGainLossFromCashFlowHedgesIncludingPortionAttributableToNoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 |
| Value | 1000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 0 | 0 | 2000000.0 | 3000000.0 | 2000000.0 | 1000000.0 | 3000000.0 | 4000000.0 | 2000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 1000000.0 | 1000000.0 | 0 | 0 | 1000000.0 | 0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 1000000.0 | 0 |
| Percentage of OtherNonoperatingIncomeExpense | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 0.3 | 0.4 | 0.7 | 0.0 | 0.0 | 3.6 | 1.3 | 3.1 | 1.8 | 5.5 | 1.7 | 3.2 | 1.7 | 1.6 | 0.4 | 0.4 | 0.4 | 0.5 | 0.0 | 0.4 | 0.4 | 0.0 | 0.0 | 0.5 | 0.0 | 0.6 | 0.7 | 0.6 | 0.0 | 0.9 | 1.2 | 1.1 | 1.3 | 0.0 | 2.4 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -1000000.0 | 1000000.0 | 0 | 1000000.0 | 0 | 0 | 1000000.0 | 0 | 0 | 1000000.0 | 0 | 0 |
| Percentage of OtherNonoperatingIncomeExpense | -100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 33.3 | 0.0 | 0.0 | 33.3 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.3 | 0.4 | 0.0 | 0.3 | 0.0 | 0.0 | 0.4 | 0.0 | 0.0 | 1.8 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 0 | 1000000.0 | 2000000.0 | 0 | 0 | 1000000.0 | 2000000.0 | 2000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 |
| Percentage of OtherNonoperatingIncomeExpense | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 50.0 | 66.7 | 100.0 | 100.0 | 33.3 | 50.0 | 50.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.3 | 0.7 | 0.0 | 0.0 | 1.8 | 0.9 | 3.1 | 1.8 | 1.8 | 0.9 | 1.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 0.0 | 1.8 | 0.0 | 0.0 | 0.0 | 14.3 | 0.0 | 22.2 | 9.1 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 1000000.0 | 1000000.0 | -1000000.0 | 0 | 1000000.0 | 0 | 0 | 0 | 0 | 1000000.0 | 0 |
| Percentage of OtherNonoperatingIncomeExpense | 100.0 | 100.0 | 0.0 | 0.0 | 50.0 | 0.0 | 0.0 | 0.0 | 0.0 | 25.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 0.3 | -0.3 | 0.0 | 1.8 | 0.0 | 0.0 | 0.0 | 0.0 | 0.4 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 1.9 | 2.0 | -1.7 | 0.0 | 2.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
| Value | 25 | 32 | -76.0 | -73.0 | 42 | 76 | -107.0 | -48.0 | 35 | -36.0 | -47.0 | -91.0 | 49 | 96 | 0.0 | -98.0 | 41 | 45 | -1.0 | -126.0 | 47 | 58 | 2.0 | 13 | 34 | 41 | -16.0 | -10.0 | 31 | 34 | 18 | 24 | 40 | 34 | 11 | 5.0 | 4.0 | -1.0 | 5.0 |
| Percentage of ProfitLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 7.1 | 8.4 | -32.1 | -26.1 | 12.7 | 23.1 | -194.5 | -20.4 | 54.7 | -63.2 | -85.5 | -39.7 | 77.8 | 165.5 | 0.0 | -42.4 | 15.5 | 15.8 | -0.5 | -54.3 | 17.3 | 22.5 | 0.9 | 6.2 | 16.3 | 18.9 | -8.9 | -6.8 | 19.3 | 25.4 | 16.4 | 27.9 | 42.1 | 43.0 | 20.8 | 11.9 | 8.5 | -2.4 | 11.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -37.0 | -41.0 | -57.0 | -32.0 | -41.0 | -10.0 | -13.0 | -52.0 | -17.0 | -33.0 | -20.0 | -79.0 | -55.0 |
| Percentage of ProfitLoss | -148.0 | -128.1 | 75.0 | 43.8 | -97.6 | -13.2 | 12.1 | 108.3 | -48.6 | 91.7 | 42.6 | 86.8 | -112.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -10.5 | -10.8 | -24.1 | -11.4 | -12.3 | -3.0 | -23.6 | -22.1 | -26.6 | -57.9 | -36.4 | -34.5 | -87.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 52 | 40 | 33 | 43 | 48 | 31 | 18 | 38 | 41 | 32 | 24 | 28 | 39 |
| Percentage of ProfitLoss | 208.0 | 125.0 | -43.4 | -58.9 | 114.3 | 40.8 | -16.8 | -79.2 | 117.1 | -88.9 | -51.1 | -30.8 | 79.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 14.8 | 10.5 | 13.9 | 15.4 | 14.5 | 9.4 | 32.7 | 16.2 | 64.1 | 56.1 | 43.6 | 12.2 | 61.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 6.0 | 27 | -56.0 | -83.0 | 34 | 54 | -114.0 | -34.0 | 6.0 | -20.0 | -56.0 | -45.0 | 55 |
| Percentage of ProfitLoss | 24.0 | 84.4 | 73.7 | 113.7 | 81.0 | 71.1 | 106.5 | 70.8 | 17.1 | 55.6 | 119.1 | 49.5 | 112.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | 7.1 | -23.6 | -29.6 | 10.2 | 16.4 | -207.3 | -14.5 | 9.4 | -35.1 | -101.8 | -19.7 | 87.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 12.5 | 49.1 | 560.0 | 0.0 | 178.9 | 300.0 | -1628.6 | 0.0 | 66.7 | -181.8 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 4.0 | 6.0 | 4.0 | -1.0 | 1.0 | 1.0 | 2.0 | 0.0 | 5.0 | -15.0 | 5.0 | 5.0 | 10.0 |
| Percentage of ProfitLoss | 16.0 | 18.8 | -5.3 | 1.4 | 2.4 | 1.3 | -1.9 | -0.0 | 14.3 | 41.7 | -10.6 | -5.5 | 20.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.1 | 1.6 | 1.7 | -0.4 | 0.3 | 0.3 | 3.6 | 0.0 | 7.8 | -26.3 | 9.1 | 2.2 | 15.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 7.4 | 12.0 | 8.2 | 0.0 | 1.7 | 2.4 | 4.2 | 0.0 | 9.1 | -32.6 | 10.0 | 0.0 | 18.9 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 0.0 | 4.0 | -16.0 | 16 | 9.0 | 1.0 |
| Percentage of ProfitLoss | 0.0 | 5.3 | 15.0 | 45.7 | -25.0 | -2.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 1.2 | -29.1 | 25.0 | 15.8 | 1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:DGPVHoldco3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 3.0 | -4.0 | -81.0 | 10.0 | 29 | -78.0 | -4.0 | -12.0 | -27.0 | 28 | 17 | -20.0 |
| Percentage of ProfitLoss | 12.0 | -12.5 | 106.6 | 23.8 | 38.2 | 72.9 | -11.4 | 33.3 | 57.4 | 57.1 | 17.7 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | -1.1 | -34.2 | 3.0 | 8.8 | -141.8 | -6.2 | -21.1 | -49.1 | 44.4 | 29.3 | -32.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 21 | 35 | 3.0 | 14 | 32 | 47 | -29.0 | 39 | -24.0 | -20.0 | 21 | 79 | 16 |
| Percentage of ProfitLoss | 84.0 | 109.4 | -3.9 | -19.2 | 76.2 | 61.8 | 27.1 | 111.4 | 66.7 | 42.6 | 42.9 | 82.3 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.0 | 9.2 | 1.3 | 5.0 | 9.6 | 14.3 | -52.7 | 60.9 | -42.1 | -36.4 | 33.3 | 136.2 | 26.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
| Value | 351 | 380 | 237 | 280 | 332 | 329 | 55 | 235 | 64 | 57 | 55 | 229 | 63 | 58 | 61 | 231 | 265 | 284 | 218 | 232 | 272 | 258 | 220 | 209 | 209 | 217 | 180 | 148 | 161 | 134 | 110 | 86 | 95 | 79 | 53 | 42 | 47 | 42 | 44 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 |
| Value | 102 | 105 | 39 | 71 | 79 | 60 | 55 | 56 | 64 | 57 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 29.1 | 27.6 | 16.5 | 25.4 | 23.8 | 18.2 | 100.0 | 23.8 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 29.1 | 27.6 | 16.5 | 25.4 | 23.8 | 18.2 | 100.0 | 23.8 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 |
| Value | 48 | 55 | -10.0 | 27 | 19 | 18 | 7.0 | 6.0 | 9.0 | 11 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 13.7 | 14.5 | -4.2 | 9.6 | 5.7 | 5.5 | 12.7 | 2.6 | 14.1 | 19.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 13.7 | 14.5 | -4.2 | 9.6 | 5.7 | 5.5 | 12.7 | 2.6 | 14.1 | 19.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 54 | 50 | 49 | 44 | 60 | 42 | 48 | 50 | 55 | 46 | 50 | 48 | 53 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 15.4 | 13.2 | 20.7 | 15.7 | 18.1 | 12.8 | 87.3 | 21.3 | 85.9 | 80.7 | 90.9 | 21.0 | 84.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 15.4 | 13.2 | 20.7 | 15.7 | 18.1 | 12.8 | 87.3 | 21.3 | 85.9 | 80.7 | 90.9 | 21.0 | 84.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
| Value | 351 | 380 | 237 | 280 | 332 | 329 | 258 | 235 | 296 | 284 | 217 | 229 | 292 | 307 | 225 | 231 | 265 | 284 | 218 | 232 | 272 | 258 | 220 | 209 | 209 | 217 | 180 | 148 | 161 | 134 | 110 | 86 | 95 | 79 | 53 | 42 | 47 | 42 | 44 |
| Percentage of Revenues | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 469.1 | 100.0 | 462.5 | 498.2 | 394.5 | 100.0 | 463.5 | 529.3 | 368.9 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 351 | 380 | 237 | 280 | 332 | 329 | 258 | 235 | 296 | 284 | 217 |
| Percentage of Revenues | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 469.1 | 100.0 | 462.5 | 498.2 | 394.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments | 344.1 | 361.9 | 607.7 | 394.4 | 420.3 | 548.3 | 469.1 | 419.6 | 462.5 | 498.2 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 133 | 128 | 120 | 126 | 143 | 124 | 121 | 108 | 103 | 99 | 92 |
| Percentage of Revenues | 37.9 | 33.7 | 50.6 | 45.0 | 43.1 | 37.7 | 46.9 | 46.0 | 34.8 | 34.9 | 42.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 37.9 | 33.7 | 50.6 | 45.0 | 43.1 | 37.7 | 220.0 | 46.0 | 160.9 | 173.7 | 167.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:CapacityRevenue | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 267 | 292 | 156 | 151 | 196 | 218 | 155 | 134 | 202 | 193 | 141 |
| Percentage of Revenues | 76.1 | 76.8 | 65.8 | 53.9 | 59.0 | 66.3 | 60.1 | 57.0 | 68.2 | 68.0 | 65.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 76.1 | 76.8 | 65.8 | 53.9 | 59.0 | 66.3 | 281.8 | 57.0 | 315.6 | 338.6 | 256.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:EnergyRevenue | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 24 | 28 | 17 | 17 | 15 | 12 | 9.0 | 12 | 11 | 9.0 | 8.0 |
| Percentage of Revenues | 6.8 | 7.4 | 7.2 | 6.1 | 4.5 | 3.6 | 3.5 | 5.1 | 3.7 | 3.2 | 3.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.8 | 7.4 | 7.2 | 6.1 | 4.5 | 3.6 | 16.4 | 5.1 | 17.2 | 15.8 | 14.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ProductsAndServicesOther | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 120 | 113 | 107 | 113 | 119 | 112 | 107 | 95 | 89 | 85 | 79 |
| Percentage of Revenues | 34.2 | 29.7 | 45.1 | 40.4 | 35.8 | 34.0 | 41.5 | 40.4 | 30.1 | 29.9 | 36.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 34.2 | 29.7 | 45.1 | 40.4 | 35.8 | 34.0 | 194.5 | 40.4 | 139.1 | 149.1 | 143.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:CapacityRevenue cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2020-06-30 | 2020-03-31 | 2019-06-30 | 2019-03-31 |
| Value | 1.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Revenues | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:CapacityRevenue cwen:Renewables | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 12 | 15 | 13 | 13 | 24 | 12 | 14 | 13 | 14 | 14 | 13 |
| Percentage of Revenues | 3.4 | 3.9 | 5.5 | 4.6 | 7.2 | 3.6 | 5.4 | 5.5 | 4.7 | 4.9 | 6.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.4 | 3.9 | 5.5 | 4.6 | 7.2 | 3.6 | 25.5 | 5.5 | 21.9 | 24.6 | 23.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:CapacityRevenue cwen:Thermal | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 3.0 | 2.0 | 1.0 | 4.0 | 3.0 | 1.0 | 2.0 | 1.0 | 2.0 | 1.0 | 1.0 |
| Percentage of Revenues | 0.9 | 0.5 | 0.4 | 1.4 | 0.9 | 0.3 | 0.8 | 0.4 | 0.7 | 0.4 | 0.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | 0.5 | 0.4 | 1.4 | 0.9 | 0.3 | 3.6 | 0.4 | 3.1 | 1.8 | 1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:EnergyRevenue cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 231 | 261 | 126 | 123 | 166 | 195 | 125 | 104 | 167 | 166 | 108 |
| Percentage of Revenues | 65.8 | 68.7 | 53.2 | 43.9 | 50.0 | 59.3 | 48.4 | 44.3 | 56.4 | 58.5 | 49.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 65.8 | 68.7 | 53.2 | 43.9 | 50.0 | 59.3 | 227.3 | 44.3 | 260.9 | 291.2 | 196.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:EnergyRevenue cwen:Renewables | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 33 | 29 | 29 | 24 | 27 | 22 | 28 | 29 | 33 | 26 | 32 |
| Percentage of Revenues | 9.4 | 7.6 | 12.2 | 8.6 | 8.1 | 6.7 | 10.9 | 12.3 | 11.1 | 9.2 | 14.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 9.4 | 7.6 | 12.2 | 8.6 | 8.1 | 6.7 | 50.9 | 12.3 | 51.6 | 45.6 | 58.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:EnergyRevenue cwen:Thermal | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 14 | 22 | 9.0 | 9.0 | 6.0 | 4.0 | 2.0 | 4.0 | 2.0 | 2.0 | 2.0 |
| Percentage of Revenues | 4.0 | 5.8 | 3.8 | 3.2 | 1.8 | 1.2 | 0.8 | 1.7 | 0.7 | 0.7 | 0.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.0 | 5.8 | 3.8 | 3.2 | 1.8 | 1.2 | 3.6 | 1.7 | 3.1 | 3.5 | 3.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ProductsAndServicesOther cwen:Renewables | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 10.0 | 6.0 | 8.0 | 8.0 | 9.0 | 8.0 | 7.0 | 8.0 | 9.0 | 7.0 | 6.0 |
| Percentage of Revenues | 2.8 | 1.6 | 3.4 | 2.9 | 2.7 | 2.4 | 2.7 | 3.4 | 3.0 | 2.5 | 2.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 2.8 | 1.6 | 3.4 | 2.9 | 2.7 | 2.4 | 12.7 | 3.4 | 14.1 | 12.3 | 10.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ProductsAndServicesOther cwen:Thermal | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 118 | 109 | 102 | 111 | 116 | 107 | 103 | 93 | 90 | 84 | 79 | 86 | 87 |
| Percentage of Revenues | 33.6 | 28.7 | 43.0 | 39.6 | 34.9 | 32.5 | 39.9 | 39.6 | 30.4 | 29.6 | 36.4 | 37.6 | 29.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 33.6 | 28.7 | 43.0 | 39.6 | 34.9 | 32.5 | 187.3 | 39.6 | 140.6 | 147.4 | 143.6 | 37.6 | 138.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 179 | 222 | 86 | 125 | 157 | 180 | 107 | 93 | 151 | 153 | 88 | 99 | 152 |
| Percentage of Revenues | 51.0 | 58.4 | 36.3 | 44.6 | 47.3 | 54.7 | 41.5 | 39.6 | 51.0 | 53.9 | 40.6 | 43.2 | 52.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 51.0 | 58.4 | 36.3 | 44.6 | 47.3 | 54.7 | 194.5 | 39.6 | 235.9 | 268.4 | 160.0 | 43.2 | 241.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 372.9 | 403.6 | -860.0 | 463.0 | 826.3 | 1000.0 | 1528.6 | 1550.0 | 1677.8 | 1390.9 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 54 | 49 | 49 | 44 | 59 | 42 | 48 | 49 | 55 | 47 | 50 | 47 | 53 |
| Percentage of Revenues | 15.4 | 12.9 | 20.7 | 15.7 | 17.8 | 12.8 | 18.6 | 20.9 | 18.6 | 16.5 | 23.0 | 20.5 | 18.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 15.4 | 12.9 | 20.7 | 15.7 | 17.8 | 12.8 | 87.3 | 20.9 | 85.9 | 82.5 | 90.9 | 20.5 | 84.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 100.0 | 98.0 | 100.0 | 100.0 | 98.3 | 100.0 | 100.0 | 98.0 | 100.0 | 102.2 | 100.0 | 97.9 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 0.0 | 7.0 | 7.0 | 9.0 | 8.0 | 4.0 |
| Percentage of Revenues | 0.0 | 2.1 | 2.7 | 3.0 | 2.8 | 1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 2.1 | 12.7 | 14.1 | 14.0 | 7.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:DGPVHoldco3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 11780 | 11881 | 11848 | 10592 | 9725 | 9736 | 9555 | 9700 | 8838 | 8731 | 8465 | 8500 | 8500 | 8448 | 8362 | 8283 | 8442 | 8513 | 8580 | 8383 | 8482 | 7607 | 7659 | 7775 | 6989 | 7208 | 6595 | 5752 | 5899 | 3236 | 2534 | 2313 | 2331 | 2074 | 1964 |
| Percentage of Assets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 2720 | 2314 | 2498 | 2777 |
| Percentage of Assets | 25.7 | 23.9 | 29.4 | 33.5 |
| Percentage of Assets | 25.7 | 23.9 | 29.4 | 33.5 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 637 |
| Percentage of Assets | 6.0 |
| Percentage of Assets | 6.0 |
| Percentage of Assets cwen:AltaTEHoldco | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 609 | 621 | 632 | 649 | 661 | 667 |
| Percentage of Assets | 5.2 | 5.2 | 5.3 | 6.7 | 6.8 | 7.0 |
| Percentage of Assets | 5.2 | 5.2 | 5.3 | 6.7 | 6.8 | 7.0 |
| Percentage of Assets cwen:AltaXandXITEHoldco | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 208 | 210 | 211 | 212 | 212 | 214 | 214 |
| Percentage of Assets | 1.8 | 1.8 | 1.8 | 2.0 | 2.2 | 2.2 | 2.2 |
| Percentage of Assets | 1.8 | 1.8 | 1.8 | 2.0 | 2.2 | 2.2 | 2.2 |
| Percentage of Assets cwen:BuckthornRenewablesLLC | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 885 |
| Percentage of Assets | 8.4 |
| Percentage of Assets | 8.4 |
| Percentage of Assets cwen:DGPVFunds | 100.0 |
| Period End | 2020-11-02 |
| Value | 424 |
| Percentage of Assets | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-05-29 |
| Value | 713 | 723 | 725 | 391 | 394 | 400 |
| Percentage of Assets | 6.1 | 6.1 | 6.1 | 4.0 | 4.0 | 0.0 |
| Percentage of Assets | 6.1 | 6.1 | 6.1 | 4.0 | 4.0 | 0.0 |
| Percentage of Assets cwen:DGPVHoldco3 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 113 | 115 |
| Percentage of Assets | 1.2 | 1.2 |
| Percentage of Assets | 1.2 | 1.2 |
| Percentage of Assets cwen:ElbowCreekTEHoldco | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 178 | 180 | 158 | 162 | 166 | 167 | 168 |
| Percentage of Assets | 1.5 | 1.5 | 1.3 | 1.5 | 1.7 | 1.7 | 1.8 |
| Percentage of Assets | 1.5 | 1.5 | 1.3 | 1.5 | 1.7 | 1.7 | 1.8 |
| Percentage of Assets cwen:KawailoaSolarPartnershipLLC | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 152 | 152 | 154 | 155 |
| Percentage of Assets | 1.3 | 1.3 | 1.3 | 1.5 |
| Percentage of Assets | 1.3 | 1.3 | 1.3 | 1.5 |
| Percentage of Assets cwen:LangfordTEPartnershipLLC | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 474 | 478 | 481 | 492 |
| Percentage of Assets | 4.0 | 4.0 | 4.1 | 4.6 |
| Percentage of Assets | 4.0 | 4.0 | 4.1 | 4.6 |
| Percentage of Assets cwen:LighthouseRenewableHoldcoLLC | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-21 |
| Value | 496 |
| Percentage of Assets | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:MesquiteStar | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 222 | 225 | 199 | 202 | 207 | 209 | 212 |
| Percentage of Assets | 1.9 | 1.9 | 1.7 | 1.9 | 2.1 | 2.1 | 2.2 |
| Percentage of Assets | 1.9 | 1.9 | 1.7 | 1.9 | 2.1 | 2.1 | 2.2 |
| Percentage of Assets cwen:OahuSolarPartnership | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 191 | 195 | 202 | 206 | 13 | 13 | 13 |
| Percentage of Assets | 1.6 | 1.6 | 1.7 | 1.9 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets | 1.6 | 1.6 | 1.7 | 1.9 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:OtherConsolidatedVariableInterestEntities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 136 | 131 | 121 |
| Percentage of Assets | 1.2 | 1.1 | 1.0 |
| Percentage of Assets | 1.2 | 1.1 | 1.0 |
| Percentage of Assets cwen:PinnacleRepoweringPartnershipHoldCoLLC | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 224 | 227 | 254 |
| Percentage of Assets | 1.9 | 1.9 | 2.1 |
| Percentage of Assets | 1.9 | 1.9 | 2.1 |
| Percentage of Assets cwen:RattlesnakeTEHoldcoLLC | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 282 | 282 | 288 | 298 |
| Percentage of Assets | 2.4 | 2.4 | 2.4 | 2.8 |
| Percentage of Assets | 2.4 | 2.4 | 2.4 | 2.8 |
| Percentage of Assets cwen:RosieTargetCoLLC | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 85 | 87 | 88 |
| Percentage of Assets | 0.9 | 0.9 | 0.9 |
| Percentage of Assets | 0.9 | 0.9 | 0.9 |
| Percentage of Assets cwen:SpringCanyon | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 251 | 253 | 255 | 254 | 260 | 268 |
| Percentage of Assets | 2.1 | 2.1 | 2.2 | 2.4 | 2.7 | 2.8 |
| Percentage of Assets | 2.1 | 2.1 | 2.2 | 2.4 | 2.7 | 2.8 |
| Percentage of Assets cwen:WildoradoTEHoldco | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2018-12-31 |
| Value | 162 | 143 | 166 | 233 | 273 | 159 | 137 | 128 | 110 | 360 |
| Percentage of Assets | 1.4 | 1.2 | 1.4 | 2.2 | 2.8 | 1.6 | 1.4 | 1.3 | 1.2 | 4.2 |
| Percentage of Assets | 1.4 | 1.2 | 1.4 | 2.2 | 2.8 | 1.6 | 1.4 | 1.3 | 1.2 | 4.2 |
| Percentage of Assets us-gaap:CorporateNonSegment | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2018-12-31 |
| Value | 2473 | 2500 | 2516 | 2575 | 2615 | 2674 | 2677 | 2753 | 1766 | 1788 |
| Percentage of Assets | 21.0 | 21.0 | 21.2 | 24.3 | 26.9 | 27.5 | 28.0 | 28.4 | 20.0 | 21.0 |
| Percentage of Assets | 21.0 | 21.0 | 21.2 | 24.3 | 26.9 | 27.5 | 28.0 | 28.4 | 20.0 | 21.0 |
| Percentage of Assets us-gaap:OperatingSegments cwen:ConventionalGeneration | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2018-12-31 |
| Value | 8522 | 8617 | 8536 | 7157 | 6210 | 6290 | 6116 | 6186 | 6330 | 5836 |
| Percentage of Assets | 72.3 | 72.5 | 72.0 | 67.6 | 63.9 | 64.6 | 64.0 | 63.8 | 71.6 | 68.7 |
| Percentage of Assets | 72.3 | 72.5 | 72.0 | 67.6 | 63.9 | 64.6 | 64.0 | 63.8 | 71.6 | 68.7 |
| Percentage of Assets us-gaap:OperatingSegments cwen:Renewables | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2018-12-31 |
| Value | 623 | 621 | 630 | 627 | 627 | 613 | 625 | 633 | 632 | 516 |
| Percentage of Assets | 5.3 | 5.2 | 5.3 | 5.9 | 6.4 | 6.3 | 6.5 | 6.5 | 7.2 | 6.1 |
| Percentage of Assets | 5.3 | 5.2 | 5.3 | 5.9 | 6.4 | 6.3 | 6.5 | 6.5 | 7.2 | 6.1 |
| Percentage of Assets us-gaap:OperatingSegments cwen:Thermal | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 8825 | 8878 | 8853 | 7877 | 7488 | 7504 | 7291 | 7437 | 6792 | 6677 | 6320 | 6276 | 6125 | 6161 | 6236 | 6145 | 6143 | 6177 | 6242 | 6013 | 6014 | 5050 | 5098 | 5143 | 4837 | 5002 | 5254 | 4272 | 4285 | 2163 | 1503 | 1302 | 1340 | 1124 |
| Percentage of Liabilities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 74.9 | 74.7 | 74.7 | 74.4 | 77.0 | 77.1 | 76.3 | 76.7 | 76.8 | 76.5 | 74.7 | 73.8 | 72.1 | 72.9 | 74.6 | 74.2 | 72.8 | 72.6 | 72.8 | 71.7 | 70.9 | 66.4 | 66.6 | 66.1 | 69.2 | 69.4 | 79.7 | 74.3 | 72.6 | 66.8 | 59.3 | 56.3 | 57.5 | 57.2 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 5.0 | 51 | 274 | 618 |
| Percentage of Liabilities | 0.1 | 0.7 | 4.4 | 10.1 |
| Percentage of Assets | 0.0 | 0.5 | 3.2 | 7.5 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 0.2 | 2.2 | 11.0 | 22.3 |
| Period End | 2020-12-31 |
| Value | 44 |
| Percentage of Liabilities | 0.6 |
| Percentage of Assets | 0.4 |
| Percentage of Assets cwen:AltaTEHoldco | 6.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 40 | 38 | 43 | 44 | 44 | 44 |
| Percentage of Liabilities | 0.5 | 0.4 | 0.5 | 0.6 | 0.6 | 0.6 |
| Percentage of Assets | 0.3 | 0.3 | 0.4 | 0.5 | 0.5 | 0.5 |
| Percentage of Assets cwen:AltaXandXITEHoldco | 6.6 | 6.1 | 6.8 | 6.8 | 6.7 | 6.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 10.0 | 10.0 | 9.0 | 9.0 | 7.0 | 7.0 | 8.0 |
| Percentage of Liabilities | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:BuckthornRenewablesLLC | 4.8 | 4.8 | 4.3 | 4.2 | 3.3 | 3.3 | 3.7 |
| Period End | 2020-12-31 |
| Value | 77 |
| Percentage of Liabilities | 1.0 |
| Percentage of Assets | 0.7 |
| Percentage of Assets cwen:DGPVFunds | 8.7 |
| Period End | 2020-11-02 |
| Value | 214 |
| Percentage of Liabilities | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 50.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-05-29 |
| Value | 77 | 77 | 76 | 276 | 281 | 290 |
| Percentage of Liabilities | 0.9 | 0.9 | 0.9 | 3.7 | 3.7 | 0.0 |
| Percentage of Assets | 0.7 | 0.6 | 0.6 | 2.8 | 2.9 | 0.0 |
| Percentage of Assets cwen:DGPVHoldco3 | 10.8 | 10.7 | 10.5 | 70.6 | 71.3 | 72.5 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 27 | 26 |
| Percentage of Liabilities | 0.4 | 0.3 |
| Percentage of Assets | 0.3 | 0.3 |
| Percentage of Assets cwen:ElbowCreekTEHoldco | 23.9 | 22.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 105 | 106 | 102 | 111 | 116 | 117 | 117 |
| Percentage of Liabilities | 1.2 | 1.2 | 1.2 | 1.4 | 1.5 | 1.6 | 1.6 |
| Percentage of Assets | 0.9 | 0.9 | 0.9 | 1.0 | 1.2 | 1.2 | 1.2 |
| Percentage of Assets cwen:KawailoaSolarPartnershipLLC | 59.0 | 58.9 | 64.6 | 68.5 | 69.9 | 70.1 | 69.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 18 | 17 | 18 | 18 |
| Percentage of Liabilities | 0.2 | 0.2 | 0.2 | 0.2 |
| Percentage of Assets | 0.2 | 0.1 | 0.2 | 0.2 |
| Percentage of Assets cwen:LangfordTEPartnershipLLC | 11.8 | 11.2 | 11.7 | 11.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 136 | 126 | 112 | 82 |
| Percentage of Liabilities | 1.5 | 1.4 | 1.3 | 1.0 |
| Percentage of Assets | 1.2 | 1.1 | 0.9 | 0.8 |
| Percentage of Assets cwen:LighthouseRenewableHoldcoLLC | 28.7 | 26.4 | 23.3 | 16.7 |
| Period End | 2020-12-21 |
| Value | 87 |
| Percentage of Liabilities | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:MesquiteStar | 17.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 115 | 117 | 114 | 122 | 125 | 127 | 129 |
| Percentage of Liabilities | 1.3 | 1.3 | 1.3 | 1.5 | 1.7 | 1.7 | 1.8 |
| Percentage of Assets | 1.0 | 1.0 | 1.0 | 1.2 | 1.3 | 1.3 | 1.4 |
| Percentage of Assets cwen:OahuSolarPartnership | 51.8 | 52.0 | 57.3 | 60.4 | 60.4 | 60.8 | 60.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 47 | 44 | 38 | 33 | 3.0 | 3.0 | 3.0 |
| Percentage of Liabilities | 0.5 | 0.5 | 0.4 | 0.4 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 0.4 | 0.4 | 0.3 | 0.3 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets cwen:OtherConsolidatedVariableInterestEntities | 24.6 | 22.6 | 18.8 | 16.0 | 23.1 | 23.1 | 23.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 119 | 102 | 81 |
| Percentage of Liabilities | 1.3 | 1.1 | 0.9 |
| Percentage of Assets | 1.0 | 0.9 | 0.7 |
| Percentage of Assets cwen:PinnacleRepoweringPartnershipHoldCoLLC | 87.5 | 77.9 | 66.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 22 | 21 | 32 |
| Percentage of Liabilities | 0.2 | 0.2 | 0.4 |
| Percentage of Assets | 0.2 | 0.2 | 0.3 |
| Percentage of Assets cwen:RattlesnakeTEHoldcoLLC | 9.8 | 9.3 | 12.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 101 | 101 | 103 | 118 |
| Percentage of Liabilities | 1.1 | 1.1 | 1.2 | 1.5 |
| Percentage of Assets | 0.9 | 0.9 | 0.9 | 1.1 |
| Percentage of Assets cwen:RosieTargetCoLLC | 35.8 | 35.8 | 35.8 | 39.6 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 5.0 | 6.0 | 5.0 |
| Percentage of Liabilities | 0.1 | 0.1 | 0.1 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:SpringCanyon | 5.9 | 6.9 | 5.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 19 | 18 | 11 | 11 | 12 | 12 |
| Percentage of Liabilities | 0.2 | 0.2 | 0.1 | 0.1 | 0.2 | 0.2 |
| Percentage of Assets | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:WildoradoTEHoldco | 7.6 | 7.1 | 4.3 | 4.3 | 4.6 | 4.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 11780 | 11881 | 11848 | 10592 | 9725 | 9736 | 9555 | 9700 | 8838 | 8731 | 8500 | 8500 | 8448 | 8362 | 8283 | 8442 | 8513 | 8580 | 8383 | 8482 | 7607 | 7659 | 7775 | 6989 | 7208 | 6595 | 5752 | 5899 | 3236 | 2534 | 2313 | 2331 | 1964 |
| Percentage of LiabilitiesAndStockholdersEquity | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 2720 | 2314 | 2498 | 2777 |
| Percentage of LiabilitiesAndStockholdersEquity | 25.7 | 23.9 | 29.4 | 33.5 |
| Percentage of Assets | 25.7 | 23.9 | 29.4 | 33.5 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-01-12 |
| Value | 107 |
| Percentage of StockholdersEquity | 100.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:ThirdPartyInvestor cwen:RattlesnakeTEHoldcoLLC us-gaap:CapitalUnitClassA | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 853 | 767 | 734 | 708 | 773 | 654 | 554 | 608 | 619 | 498 | 456 | 756 | 603 | 472 | 425 | 482 | 520 | 491 | 476 | 645 | 531 | 319 | 284 | 318 | 376 | 491 | 293 | 539 | 555 | 196 | 502 | 267 | 408 | 81 |
| Percentage of AssetsCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 7.2 | 6.5 | 6.2 | 6.7 | 7.9 | 6.7 | 5.8 | 6.3 | 7.0 | 5.7 | 5.4 | 8.9 | 7.1 | 5.6 | 5.1 | 5.8 | 6.2 | 5.8 | 5.5 | 7.7 | 6.3 | 4.2 | 3.7 | 4.1 | 5.4 | 6.8 | 4.4 | 9.4 | 9.4 | 6.1 | 19.8 | 11.5 | 17.5 | 4.1 |
| Period End | 2020-11-02 |
| Value | 29 |
| Percentage of AssetsCurrent | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 6.8 |
| Period End | 2020-12-21 |
| Value | 22 |
| Percentage of AssetsCurrent | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:MesquiteStar | 4.4 |
| Period End | 2020-12-31 | 2020-06-30 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 132 | 261 | 209 | 133 | 133 |
| Percentage of AssetsCurrent | 18.6 | 39.9 | 34.4 | 17.6 | 27.6 |
| Percentage of Assets | 1.2 | 2.7 | 2.2 | 1.6 | 1.6 |
| Percentage of Assets cwen:DesertSunlight | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 40 | 37 |
| Percentage of AssetsCurrent | 5.6 | 6.1 |
| Percentage of Assets | 0.4 | 0.4 |
| Percentage of Assets cwen:GenConn | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 177 | 195 | 148 | 139 |
| Percentage of AssetsCurrent | 25.0 | 32.1 | 19.6 | 28.8 |
| Percentage of Assets | 1.7 | 2.0 | 1.7 | 1.7 |
| Percentage of Assets cwen:InvestmentsOther | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2011-12-31 | 2010-12-31 |
| Value | 189 | 138 | 144 | 268 | 359 | 175 | 110 | 155 | 148 | 93 | 117 | 407 | 232 | 130 | 173 | 148 | 179 | 181 | 213 | 317 | 200 | 89 | 76 | 111 | 125 | 281 | 114 | 391 | 372 | 87 | 420 | 36 | 121 | 18 | 23 | 22 | 30 | 24 | 30 |
| Percentage of CashAndCashEquivalentsAtCarryingValue | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 1.6 | 1.2 | 1.2 | 2.5 | 3.7 | 1.8 | 1.2 | 1.6 | 1.7 | 1.1 | 1.4 | 4.8 | 2.7 | 1.5 | 2.1 | 1.8 | 2.1 | 2.1 | 2.5 | 3.8 | 2.4 | 1.2 | 1.0 | 1.4 | 1.8 | 3.9 | 1.7 | 6.8 | 6.3 | 2.7 | 16.6 | 1.6 | 5.2 | 0.9 | 0.0 | 1.1 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2015-12-31 | 2014-12-31 |
| Value | 555 | 470 | 431 | 465 | 537 | 416 | 380 | 417 | 397 | 296 | 298 | 583 | 389 | 269 | 277 | 316 | 319 | 295 | 323 | 487 | 338 | 213 | 242 | 573 |
| Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 4.7 | 4.0 | 3.6 | 4.4 | 5.5 | 4.3 | 4.0 | 4.3 | 4.5 | 3.4 | 3.5 | 6.9 | 4.6 | 3.2 | 3.3 | 3.8 | 3.8 | 3.5 | 3.8 | 5.8 | 4.0 | 2.8 | 3.1 | 10.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2012-12-31 |
| Value | 203 | 203 | 159 | 143 | 156 | 161 | 99 | 116 | 141 | 126 | 91 | 104 | 141 | 132 | 82 | 95 | 126 | 119 | 82 | 91 | 115 | 109 | 85 | 95 | 104 | 98 | 63 | 67 | 80 | 56 | 38 | 40 | 22 |
| Percentage of AccountsReceivableNetCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 1.7 | 1.7 | 1.3 | 1.4 | 1.6 | 1.7 | 1.0 | 1.2 | 1.6 | 1.4 | 1.1 | 1.2 | 1.7 | 1.6 | 1.0 | 1.1 | 1.5 | 1.4 | 1.0 | 1.1 | 1.4 | 1.4 | 1.1 | 1.2 | 1.5 | 1.4 | 1.0 | 1.2 | 1.4 | 1.7 | 1.5 | 1.7 | 1.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 42 | 43 | 43 | 42 | 42 | 41 | 41 | 40 | 43 | 49 | 40 | 40 | 39 | 39 | 39 | 39 | 38 | 41 | 40 | 39 | 37 | 35 | 34 | 35 | 30 | 29 | 27 | 18 | 17 | 14 | 15 | 14 | 9.0 | 5.0 |
| Percentage of InventoryNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.5 | 0.6 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.4 | 0.5 | 0.4 | 0.5 | 0.4 | 0.4 | 0.4 | 0.3 | 0.3 | 0.4 | 0.6 | 0.6 | 0.4 | 0.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 51 | 50 | 101 | 58 | 38 | 36 | 33 | 33 | 34 | 26 | 27 | 29 | 31 | 26 | 18 | 19 | 22 | 21 | 19 | 16 | 21 | 22 | 20 | 22 | 25 | 19 | 18 | 19 | 22 | 7.0 | 4.0 | 17 | 18 | 2.0 |
| Percentage of PrepaidExpenseAndOtherAssetsCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.4 | 0.4 | 0.9 | 0.5 | 0.4 | 0.4 | 0.3 | 0.3 | 0.4 | 0.3 | 0.3 | 0.3 | 0.4 | 0.3 | 0.2 | 0.2 | 0.3 | 0.2 | 0.2 | 0.2 | 0.2 | 0.3 | 0.3 | 0.3 | 0.4 | 0.3 | 0.3 | 0.3 | 0.4 | 0.2 | 0.2 | 0.7 | 0.8 | 0.1 |
| Period End | 2020-12-31 | 2020-06-30 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 1244 | 1271 | 1296 | 1298 | 1350 |
| Percentage of AssetsNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 11.7 | 13.1 | 13.4 | 15.3 | 16.3 |
| Percentage of Assets cwen:DesertSunlight | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 344 | 342 |
| Percentage of AssetsNoncurrent | 27.7 | 26.4 |
| Percentage of Assets | 3.2 | 3.5 |
| Percentage of Assets cwen:GenConn | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 2201 | 2514 | 2511 | 2621 |
| Percentage of AssetsNoncurrent | 176.9 | 194.0 | 193.5 | 194.1 |
| Percentage of Assets | 20.8 | 25.9 | 29.5 | 31.6 |
| Percentage of Assets cwen:InvestmentsOther | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 9540 | 7943 | 6835 | 6489 | 6411 | 5779 | 5757 | 4933 | 4927 | 4821 | 3795 | 3542 | 2488 | 1711 | 1705 | 1636 | 1626 | 1713 |
| Percentage of PropertyPlantAndEquipmentGross | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 90.1 | 81.9 | 80.4 | 78.3 | 76.5 | 75.5 | 74.0 | 70.6 | 68.4 | 73.1 | 66.0 | 60.0 | 76.9 | 67.5 | 73.7 | 70.2 | 78.4 | 87.2 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 7201 | 6975 | 6974 | 7020 | 6942 |
| Percentage of PropertyPlantAndEquipmentGross | 75.5 | 0.0 | 0.0 | 0.0 | 87.4 |
| Percentage of Assets | 68.0 | 71.7 | 71.6 | 73.5 | 71.6 |
| Percentage of Assets us-gaap:AssetsLeasedToOthers | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 62 | 94 | 26 | 238 | 7.0 | 11 | 8.0 | 6.0 | 5.0 | 2.0 | 930 |
| Percentage of PropertyPlantAndEquipmentGross | 0.6 | 1.2 | 0.4 | 3.7 | 0.2 | 0.4 | 0.5 | 0.4 | 0.3 | 0.1 | 54.3 |
| Percentage of Assets | 0.6 | 1.0 | 0.3 | 2.9 | 0.1 | 0.3 | 0.3 | 0.3 | 0.2 | 0.1 | 47.4 |
| Percentage of Assets us-gaap:ConstructionInProgress | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 224 | 173 | 171 | 166 | 171 | 151 | 151 | 92 | 87 | 87 | 87 | 45 | 34 | 35 | 30 |
| Percentage of PropertyPlantAndEquipmentGross | 2.3 | 2.2 | 2.5 | 2.6 | 2.7 | 2.6 | 2.6 | 1.9 | 1.8 | 1.8 | 2.3 | 2.6 | 2.1 | 2.2 | 1.8 |
| Percentage of Assets | 2.1 | 1.8 | 2.0 | 2.0 | 2.0 | 2.0 | 1.9 | 1.3 | 1.2 | 1.3 | 1.5 | 1.9 | 1.5 | 1.7 | 1.5 |
| Percentage of Assets us-gaap:LandAndLandImprovements | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 9254 | 7676 | 6638 | 6289 | 6215 | 5602 | 5597 | 4837 | 4832 | 4717 | 3701 | 1654 | 680 |
| Percentage of PropertyPlantAndEquipmentGross | 97.0 | 96.6 | 97.1 | 96.9 | 96.9 | 96.9 | 97.2 | 98.1 | 98.1 | 97.8 | 97.5 | 97.0 | 39.7 |
| Percentage of Assets | 87.4 | 79.1 | 78.1 | 75.9 | 74.1 | 73.1 | 72.0 | 69.2 | 67.0 | 71.5 | 64.3 | 71.5 | 34.6 |
| Percentage of Assets us-gaap:SupportEquipmentAndFacilities | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 2700 | 2573 | 2447 | 2323 | 2135 | 2036 | 1970 | 1880 | 1830 | 1731 | 1674 | 1590 | 1507 | 1428 | 1358 | 1285 | 1189 | 1102 | 1025 | 951 | 1002 | 832 | 767 | 701 | 499 | 449 | 391 | 308 | 266 | 233 | 181 | 164 | 149 | 134 | 115 |
| Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 22.9 | 21.7 | 20.7 | 21.9 | 22.0 | 20.9 | 20.6 | 19.4 | 20.7 | 19.8 | 19.8 | 18.7 | 17.7 | 16.9 | 16.2 | 15.5 | 14.1 | 12.9 | 11.9 | 11.3 | 11.8 | 10.9 | 10.0 | 9.0 | 7.1 | 6.2 | 5.9 | 5.4 | 4.5 | 7.2 | 7.1 | 7.1 | 6.4 | 6.5 | 5.9 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 |
| Value | 1964 | 1854 | 1769 | 1732 | 1649 | 1509 | 1435 |
| Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment | 84.5 | 86.8 | 86.9 | 87.9 | 87.7 | 87.2 | 85.7 |
| Percentage of Assets | 18.5 | 19.1 | 18.2 | 18.1 | 17.0 | 17.3 | 17.0 |
| Percentage of Assets us-gaap:AssetsLeasedToOthers | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 7438 | 7537 | 7490 | 7217 | 6165 | 6256 | 6001 | 6063 | 5562 | 5602 | 5355 | 5245 | 5306 | 5376 | 5340 | 5204 | 5247 | 5322 | 5390 | 5460 | 5711 | 4947 | 5012 | 5056 | 4434 | 4478 | 4430 | 3487 | 3276 | 2255 | 1530 | 1541 | 1487 | 1492 | 1598 |
| Percentage of PropertyPlantAndEquipmentNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 63.1 | 63.4 | 63.2 | 68.1 | 63.4 | 64.3 | 62.8 | 62.5 | 62.9 | 64.2 | 63.3 | 61.7 | 62.4 | 63.6 | 63.9 | 62.8 | 62.2 | 62.5 | 62.8 | 65.1 | 67.3 | 65.0 | 65.4 | 65.0 | 63.4 | 62.1 | 67.2 | 60.6 | 55.5 | 69.7 | 60.4 | 66.6 | 63.8 | 71.9 | 81.4 |
| Period End | 2020-12-31 |
| Value | 356 |
| Percentage of PropertyPlantAndEquipmentNet | 4.9 |
| Percentage of Assets | 3.4 |
| Percentage of Assets cwen:AltaTEHoldco | 55.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 338 | 344 | 351 | 363 | 369 | 376 |
| Percentage of PropertyPlantAndEquipmentNet | 4.5 | 4.6 | 4.7 | 5.9 | 5.9 | 6.3 |
| Percentage of Assets | 2.9 | 2.9 | 3.0 | 3.7 | 3.8 | 3.9 |
| Percentage of Assets cwen:AltaXandXITEHoldco | 55.5 | 55.4 | 55.5 | 55.9 | 55.8 | 56.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 204 | 206 | 208 | 210 | 209 | 211 | 213 |
| Percentage of PropertyPlantAndEquipmentNet | 2.7 | 2.7 | 2.8 | 2.9 | 3.4 | 3.4 | 3.5 |
| Percentage of Assets | 1.7 | 1.7 | 1.8 | 2.0 | 2.1 | 2.2 | 2.2 |
| Percentage of Assets cwen:BuckthornRenewablesLLC | 98.1 | 98.1 | 98.6 | 99.1 | 98.6 | 98.6 | 99.5 |
| Period End | 2020-12-31 |
| Value | 778 |
| Percentage of PropertyPlantAndEquipmentNet | 10.8 |
| Percentage of Assets | 7.3 |
| Percentage of Assets cwen:DGPVFunds | 87.9 |
| Period End | 2020-11-02 |
| Value | 324 |
| Percentage of PropertyPlantAndEquipmentNet | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 76.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-05-29 |
| Value | 602 | 611 | 621 | 329 | 330 | 330 |
| Percentage of PropertyPlantAndEquipmentNet | 8.1 | 8.1 | 8.3 | 5.3 | 5.3 | 0.0 |
| Percentage of Assets | 5.1 | 5.1 | 5.2 | 3.4 | 3.4 | 0.0 |
| Percentage of Assets cwen:DGPVHoldco3 | 84.4 | 84.5 | 85.7 | 84.1 | 83.8 | 82.5 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 102 | 104 |
| Percentage of PropertyPlantAndEquipmentNet | 1.7 | 1.7 |
| Percentage of Assets | 1.0 | 1.1 |
| Percentage of Assets cwen:ElbowCreekTEHoldco | 90.3 | 90.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 137 | 138 | 118 | 141 | 142 | 144 | 145 |
| Percentage of PropertyPlantAndEquipmentNet | 1.8 | 1.8 | 1.6 | 2.0 | 2.3 | 2.3 | 2.4 |
| Percentage of Assets | 1.2 | 1.2 | 1.0 | 1.3 | 1.5 | 1.5 | 1.5 |
| Percentage of Assets cwen:KawailoaSolarPartnershipLLC | 77.0 | 76.7 | 74.7 | 87.0 | 85.5 | 86.2 | 86.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 133 | 135 | 137 | 138 |
| Percentage of PropertyPlantAndEquipmentNet | 1.8 | 1.8 | 1.8 | 1.9 |
| Percentage of Assets | 1.1 | 1.1 | 1.2 | 1.3 |
| Percentage of Assets cwen:LangfordTEPartnershipLLC | 87.5 | 88.8 | 89.0 | 89.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 432 | 437 | 442 | 444 |
| Percentage of PropertyPlantAndEquipmentNet | 5.8 | 5.8 | 5.9 | 6.2 |
| Percentage of Assets | 3.7 | 3.7 | 3.7 | 4.2 |
| Percentage of Assets cwen:LighthouseRenewableHoldcoLLC | 91.1 | 91.4 | 91.9 | 90.2 |
| Period End | 2020-12-21 |
| Value | 443 |
| Percentage of PropertyPlantAndEquipmentNet | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:MesquiteStar | 89.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 174 | 175 | 150 | 179 | 182 | 183 | 185 |
| Percentage of PropertyPlantAndEquipmentNet | 2.3 | 2.3 | 2.0 | 2.5 | 3.0 | 2.9 | 3.1 |
| Percentage of Assets | 1.5 | 1.5 | 1.3 | 1.7 | 1.9 | 1.9 | 1.9 |
| Percentage of Assets cwen:OahuSolarPartnership | 78.4 | 77.8 | 75.4 | 88.6 | 87.9 | 87.6 | 87.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 175 | 178 | 181 | 184 | 8.0 | 8.0 | 8.0 |
| Percentage of PropertyPlantAndEquipmentNet | 2.4 | 2.4 | 2.4 | 2.5 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets | 1.5 | 1.5 | 1.5 | 1.7 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:OtherConsolidatedVariableInterestEntities | 91.6 | 91.3 | 89.6 | 89.3 | 61.5 | 61.5 | 61.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 106 | 100 | 91 |
| Percentage of PropertyPlantAndEquipmentNet | 1.4 | 1.3 | 1.2 |
| Percentage of Assets | 0.9 | 0.8 | 0.8 |
| Percentage of Assets cwen:PinnacleRepoweringPartnershipHoldCoLLC | 77.9 | 76.3 | 75.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 194 | 196 | 211 |
| Percentage of PropertyPlantAndEquipmentNet | 2.6 | 2.6 | 2.8 |
| Percentage of Assets | 1.6 | 1.6 | 1.8 |
| Percentage of Assets cwen:RattlesnakeTEHoldcoLLC | 86.6 | 86.3 | 83.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 253 | 255 | 256 | 258 |
| Percentage of PropertyPlantAndEquipmentNet | 3.4 | 3.4 | 3.4 | 3.6 |
| Percentage of Assets | 2.1 | 2.1 | 2.2 | 2.4 |
| Percentage of Assets cwen:RosieTargetCoLLC | 89.7 | 90.4 | 88.9 | 86.6 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 82 | 84 | 85 |
| Percentage of PropertyPlantAndEquipmentNet | 1.3 | 1.3 | 1.4 |
| Percentage of Assets | 0.8 | 0.9 | 0.9 |
| Percentage of Assets cwen:SpringCanyon | 96.5 | 96.6 | 96.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 229 | 232 | 236 | 240 | 244 | 249 |
| Percentage of PropertyPlantAndEquipmentNet | 3.1 | 3.1 | 3.2 | 3.3 | 4.0 | 4.0 |
| Percentage of Assets | 1.9 | 2.0 | 2.0 | 2.3 | 2.5 | 2.6 |
| Percentage of Assets cwen:WildoradoTEHoldco | 91.2 | 91.7 | 92.5 | 94.5 | 93.8 | 92.9 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 |
| Value | 5237 | 5121 | 5205 | 5288 | 5293 | 4555 | 4638 |
| Percentage of PropertyPlantAndEquipmentNet | 72.6 | 83.1 | 83.2 | 88.1 | 87.3 | 81.3 | 86.6 |
| Percentage of Assets | 49.4 | 52.7 | 53.5 | 55.3 | 54.6 | 52.2 | 54.8 |
| Percentage of Assets us-gaap:AssetsLeasedToOthers | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 2612 | 2173 | 2182 | 2029 |
| Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 24.7 | 22.4 | 25.7 | 24.5 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 96.0 | 93.9 | 87.3 | 73.1 |
| Period End | 2020-11-02 |
| Value | 19 |
| Percentage of IntangibleAssetsNetExcludingGoodwill | 100.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 4.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 2154 | 2188 | 2223 | 1370 | 1371 | 1393 | 1406 | 1428 | 1103 | 1121 | 1139 | 1156 | 1177 | 1192 | 1210 | 1228 | 1234 | 1251 | 1268 | 1286 | 1303 | 1321 | 1338 | 1362 | 1377 | 1389 | 1403 | 1266 | 1517 | 105 | 85 | 86 | 27 | 30 |
| Percentage of FiniteLivedIntangibleAssetsNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 18.3 | 18.4 | 18.8 | 12.9 | 14.1 | 14.3 | 14.7 | 14.7 | 12.5 | 12.8 | 13.5 | 13.6 | 13.8 | 14.1 | 14.5 | 14.8 | 14.6 | 14.7 | 14.8 | 15.3 | 15.4 | 17.4 | 17.5 | 17.5 | 19.7 | 19.3 | 21.3 | 22.0 | 25.7 | 3.2 | 3.4 | 3.7 | 1.2 | 1.5 |
| Period End | 2020-12-31 |
| Value | 225 |
| Percentage of FiniteLivedIntangibleAssetsNet | 16.4 |
| Percentage of Assets | 2.1 |
| Percentage of Assets cwen:AltaTEHoldco | 35.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 215 | 218 | 221 | 228 | 231 | 234 |
| Percentage of FiniteLivedIntangibleAssetsNet | 10.0 | 10.0 | 9.9 | 16.6 | 16.6 | 16.6 |
| Percentage of Assets | 1.8 | 1.8 | 1.9 | 2.3 | 2.4 | 2.4 |
| Percentage of Assets cwen:AltaXandXITEHoldco | 35.3 | 35.1 | 35.0 | 35.1 | 34.9 | 35.1 |
| Period End | 2020-12-31 |
| Value | 2.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.1 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVFunds | 0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-05-29 |
| Value | 16 | 16 | 16 | 1.0 | 1.0 | 1.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.7 | 0.7 | 0.7 | 0.1 | 0.1 | 0.0 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets cwen:DGPVHoldco3 | 2.2 | 2.2 | 2.2 | 0.3 | 0.3 | 0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-06-30 | 2020-03-31 |
| Value | 1.0 | 1.0 | 1.0 | 1.0 | 0.0 | 0.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.0 | 0.0 | 0.0 | 0.1 | 0.0 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets cwen:OtherConsolidatedVariableInterestEntities | 0.5 | 0.5 | 0.5 | 0.5 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 19 | 19 | 20 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.9 | 0.9 | 0.9 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 |
| Percentage of Assets cwen:PinnacleRepoweringPartnershipHoldCoLLC | 14.0 | 14.5 | 16.5 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 14 | 15 | 7.0 | 6.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 1.0 | 1.1 | 0.6 | 0.5 |
| Percentage of Assets | 0.1 | 0.2 | 0.1 | 0.1 |
| Percentage of Assets cwen:EmissionAllowances | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 60 | 64 | 68 | 73 |
| Percentage of FiniteLivedIntangibleAssetsNet | 4.4 | 4.5 | 5.9 | 5.9 |
| Percentage of Assets | 0.6 | 0.7 | 0.8 | 0.9 |
| Percentage of Assets cwen:LeaseholdRights | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 1230 | 1283 |
| Percentage of FiniteLivedIntangibleAssetsNet | 89.8 | 89.8 |
| Percentage of Assets | 11.6 | 13.2 |
| Percentage of Assets cwen:PPAs | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 4.0 | 5.0 | 6.0 | 7.0 | 8.0 | 9.0 | 10.0 | 11 | 12 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.3 | 0.4 | 0.5 | 0.6 | 0.6 | 0.7 | 0.8 | 12.8 | 40.0 |
| Percentage of Assets | 0.0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.5 | 0.6 |
| Percentage of Assets us-gaap:CustomerContracts | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 55 | 57 | 59 | 61 | 62 | 63 | 64 | 65 | 7.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 4.0 | 4.0 | 5.1 | 5.0 | 4.8 | 4.6 | 5.1 | 75.6 | 23.3 |
| Percentage of Assets | 0.5 | 0.6 | 0.7 | 0.7 | 0.7 | 0.8 | 1.1 | 2.8 | 0.4 |
| Percentage of Assets us-gaap:CustomerRelationships | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 7.0 | 4.0 | 5.0 | 4.0 | 4.0 | 4.0 | 3.0 | 3.0 | 3.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 0.5 | 0.3 | 0.4 | 0.3 | 0.3 | 0.3 | 0.2 | 3.5 | 10.0 |
| Percentage of Assets | 0.1 | 0.0 | 0.1 | 0.0 | 0.0 | 0.1 | 0.1 | 0.1 | 0.2 |
| Percentage of Assets us-gaap:OtherIntangibleAssets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 104 | 92 | 57 | 128 | 216 | 170 | 134 | 146 | -3.0 |
| Percentage of DeferredTaxAssetsLiabilitiesNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 1.0 | 0.9 | 0.7 | 1.5 | 2.6 | 2.2 | 2.3 | 6.3 | -0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-01-01 | 2018-12-31 |
| Value | 346 | 349 | 348 | 337 | 256 | 257 | 221 | 223 | 191 | 183 | 168 | 0.0 |
| Percentage of OperatingLeaseRightOfUseAsset | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Percentage of Assets | 2.9 | 2.9 | 2.9 | 3.2 | 2.6 | 2.6 | 2.3 | 2.3 | 2.2 | 2.1 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-12-31 |
| Value | 18 | 18 | 18 | 19 |
| Percentage of OperatingLeaseRightOfUseAsset | 5.3 | 7.0 | 7.0 | 8.5 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 | 0.2 |
| Percentage of Assets cwen:OahuSolarPartnership | 0.0 | 0.0 | 0.0 | 8.8 |
| Period End | 2020-12-31 |
| Value | 11 |
| Percentage of OperatingLeaseRightOfUseAsset | 3.3 |
| Percentage of Assets | 0.1 |
| Percentage of Assets cwen:RosamondCentral | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 104 | 144 | 139 | 114 | 75 | 110 | 108 | 103 | 109 | 100 | 128 | 106 | 92 | 82 | 73 | 63 | 56 | 74 | 66 | 51 | 47 | 66 | 58 | 61 | 114 | 144 | 123 | 99 | 93 | 93 | 32 | 27 | 26 | 21 |
| Percentage of OtherAssetsNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.9 | 1.2 | 1.2 | 1.1 | 0.8 | 1.1 | 1.1 | 1.1 | 1.2 | 1.1 | 1.5 | 1.2 | 1.1 | 1.0 | 0.9 | 0.8 | 0.7 | 0.9 | 0.8 | 0.6 | 0.6 | 0.9 | 0.8 | 0.8 | 1.6 | 2.0 | 1.9 | 1.7 | 1.6 | 2.9 | 1.3 | 1.2 | 1.1 | 1.1 |
| Period End | 2020-11-02 |
| Value | 52 |
| Percentage of OtherAssetsNoncurrent | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:DGPVHoldco1And2 | 12.3 |
| Period End | 2020-12-21 |
| Value | 31 |
| Percentage of OtherAssetsNoncurrent | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:MesquiteStar | 6.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 3489 | 3577 | 3624 | 2667 | 2787 | 2826 | 3000 | 3029 | 2631 | 2654 | 2499 | 2591 | 2600 | 2597 | 2597 | 2675 | 2700 | 2714 | 2278 | 2240 | 2341 | 2363 | 2401 | 2179 | 2239 | 1872 | 1726 | 505 | 285 |
| Percentage of OtherAssets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 29.6 | 30.1 | 30.6 | 25.2 | 28.7 | 29.0 | 31.4 | 31.2 | 30.1 | 31.4 | 29.4 | 30.5 | 30.8 | 31.1 | 31.4 | 31.7 | 31.7 | 31.6 | 27.2 | 26.4 | 30.8 | 30.9 | 30.9 | 31.2 | 31.1 | 28.4 | 30.0 | 21.8 | 14.5 |
| Period End | 2020-12-31 |
| Value | 56 |
| Percentage of OtherAssets | 2.1 |
| Percentage of Assets | 0.5 |
| Percentage of Assets cwen:AltaTEHoldco | 8.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 56 | 59 | 60 | 58 | 61 | 57 |
| Percentage of OtherAssets | 1.6 | 1.6 | 1.7 | 2.1 | 2.2 | 1.9 |
| Percentage of Assets | 0.5 | 0.5 | 0.5 | 0.6 | 0.6 | 0.6 |
| Percentage of Assets cwen:AltaXandXITEHoldco | 9.2 | 9.5 | 9.5 | 8.9 | 9.2 | 8.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 4.0 | 4.0 | 3.0 | 2.0 | 3.0 | 3.0 | 1.0 |
| Percentage of OtherAssets | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets cwen:BuckthornRenewablesLLC | 1.9 | 1.9 | 1.4 | 0.9 | 1.4 | 1.4 | 0.5 |
| Period End | 2020-12-31 |
| Value | 105 |
| Percentage of OtherAssets | 3.9 |
| Percentage of Assets | 1.0 |
| Percentage of Assets cwen:DGPVFunds | 11.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 |
| Value | 95 | 96 | 88 | 61 | 63 |
| Percentage of OtherAssets | 2.7 | 2.7 | 2.4 | 2.2 | 2.2 |
| Percentage of Assets | 0.8 | 0.8 | 0.7 | 0.6 | 0.6 |
| Percentage of Assets cwen:DGPVHoldco3 | 13.3 | 13.3 | 12.1 | 15.6 | 16.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 41 | 42 | 40 | 21 | 24 | 23 | 23 |
| Percentage of OtherAssets | 1.2 | 1.2 | 1.1 | 0.8 | 0.9 | 0.8 | 0.8 |
| Percentage of Assets | 0.3 | 0.4 | 0.3 | 0.2 | 0.2 | 0.2 | 0.2 |
| Percentage of Assets cwen:KawailoaSolarPartnershipLLC | 23.0 | 23.3 | 25.3 | 13.0 | 14.5 | 13.8 | 13.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 17 | 15 | 15 | 15 |
| Percentage of OtherAssets | 0.5 | 0.4 | 0.4 | 0.6 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:LangfordTEPartnershipLLC | 11.2 | 9.9 | 9.7 | 9.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 42 | 41 | 39 | 48 |
| Percentage of OtherAssets | 1.2 | 1.1 | 1.1 | 1.8 |
| Percentage of Assets | 0.4 | 0.3 | 0.3 | 0.5 |
| Percentage of Assets cwen:LighthouseRenewableHoldcoLLC | 8.9 | 8.6 | 8.1 | 9.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 48 | 50 | 49 | 23 | 25 | 26 | 27 |
| Percentage of OtherAssets | 1.4 | 1.4 | 1.4 | 0.9 | 0.9 | 0.9 | 0.9 |
| Percentage of Assets | 0.4 | 0.4 | 0.4 | 0.2 | 0.3 | 0.3 | 0.3 |
| Percentage of Assets cwen:OahuSolarPartnership | 21.6 | 22.2 | 24.6 | 11.4 | 12.1 | 12.4 | 12.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 15 | 16 | 20 | 21 | 5.0 | 5.0 | 5.0 |
| Percentage of OtherAssets | 0.4 | 0.4 | 0.6 | 0.8 | 0.2 | 0.2 | 0.2 |
| Percentage of Assets | 0.1 | 0.1 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:OtherConsolidatedVariableInterestEntities | 7.9 | 8.2 | 9.9 | 10.2 | 38.5 | 38.5 | 38.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 11 | 12 | 10.0 |
| Percentage of OtherAssets | 0.3 | 0.3 | 0.3 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:PinnacleRepoweringPartnershipHoldCoLLC | 8.1 | 9.2 | 8.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 30 | 31 | 43 |
| Percentage of OtherAssets | 0.9 | 0.9 | 1.2 |
| Percentage of Assets | 0.3 | 0.3 | 0.4 |
| Percentage of Assets cwen:RattlesnakeTEHoldcoLLC | 13.4 | 13.7 | 16.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 29 | 27 | 32 | 40 |
| Percentage of OtherAssets | 0.8 | 0.8 | 0.9 | 1.5 |
| Percentage of Assets | 0.2 | 0.2 | 0.3 | 0.4 |
| Percentage of Assets cwen:RosieTargetCoLLC | 10.3 | 9.6 | 11.1 | 13.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 22 | 21 | 19 | 14 | 16 | 19 |
| Percentage of OtherAssets | 0.6 | 0.6 | 0.5 | 0.5 | 0.6 | 0.7 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 | 0.1 | 0.2 | 0.2 |
| Percentage of Assets cwen:WildoradoTEHoldco | 8.8 | 8.3 | 7.5 | 5.5 | 6.2 | 7.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 58 | 59 | 93 | 72 | 46 | 41 | 74 | 62 | 55 | 45 | 90 | 40 | 40 | 27 | 27 | 23 | 26 | 23 | 23 | 21 | 26 | 23 | 22 | 23 | 33 | 19 | 40 | 166 |
| Percentage of AccountsPayableCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.5 | 0.5 | 0.8 | 0.7 | 0.5 | 0.4 | 0.8 | 0.7 | 0.6 | 0.5 | 1.1 | 0.5 | 0.5 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.5 | 0.3 | 1.7 | 8.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 816 | 754 | 748 | 634 | 602 | 555 | 1714 | 2057 | 2246 | 2127 | 1787 | 704 | 1085 | 804 | 859 | 486 | 490 | 438 | 455 | 459 | 459 | 380 | 383 | 456 | 425 | 570 | 389 | 297 | 302 | 233 | 150 | 257 | 267 | 285 |
| Percentage of LiabilitiesCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 6.9 | 6.3 | 6.3 | 6.0 | 6.2 | 5.7 | 17.9 | 21.2 | 25.4 | 24.4 | 21.1 | 8.3 | 12.8 | 9.5 | 10.3 | 5.9 | 5.8 | 5.1 | 5.3 | 5.5 | 5.4 | 5.0 | 5.0 | 5.9 | 6.1 | 7.9 | 5.9 | 5.2 | 5.1 | 7.2 | 5.9 | 11.1 | 11.5 | 14.5 |
| Period End | 2020-12-31 | 2020-06-30 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 71 | 545 | 545 | 58 | 64 |
| Percentage of LiabilitiesCurrent | 11.2 | 98.2 | 26.5 | 8.2 | 13.2 |
| Percentage of Assets | 0.7 | 5.6 | 5.6 | 0.7 | 0.8 |
| Percentage of Assets cwen:DesertSunlight | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 17 | 16 |
| Percentage of LiabilitiesCurrent | 2.7 | 0.8 |
| Percentage of Assets | 0.2 | 0.2 |
| Percentage of Assets cwen:GenConn | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 114 | 767 | 58 | 60 |
| Percentage of LiabilitiesCurrent | 18.0 | 37.3 | 8.2 | 12.3 |
| Percentage of Assets | 1.1 | 7.9 | 0.7 | 0.7 |
| Percentage of Assets cwen:InvestmentsOther | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 545 | 518 | 500 | 384 | 361 | 357 | 1480 | 1824 | 1965 | 1914 | 1608 | 535 | 241 | 224 | 407 | 218 | 160 | 157 | 119 | 71 | 133 | 147 | 126 | 58 |
| Percentage of LongTermDebtCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 4.6 | 4.4 | 4.2 | 3.6 | 3.7 | 3.7 | 15.5 | 18.8 | 22.2 | 21.9 | 19.0 | 6.3 | 3.1 | 3.2 | 5.6 | 3.3 | 2.8 | 2.7 | 3.7 | 2.8 | 5.8 | 6.3 | 6.1 | 3.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 8000000.0 | 7000000.0 | 7000000.0 | 7000000.0 | 7000000.0 |
| Percentage of OperatingLeaseLiabilityCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2014-12-31 |
| Value | 104 | 64 | 62 | 79 | 89 | 40 | 39 | 71 | 42 | 35 | 57 | 96 | 60 | 58 | 88 | 95 | 60 | 55 | 85 | 94 | 39 | 53 | 68 | 79 | 61 |
| Percentage of OtherAccruedLiabilitiesCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.9 | 0.5 | 0.5 | 0.7 | 0.9 | 0.4 | 0.4 | 0.7 | 0.5 | 0.4 | 0.7 | 1.1 | 0.7 | 0.7 | 1.1 | 1.1 | 0.7 | 0.6 | 1.0 | 1.1 | 0.5 | 0.7 | 0.9 | 1.1 | 1.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 8009 | 8124 | 8105 | 7243 | 6886 | 6949 | 5577 | 5380 | 4546 | 4550 | 4533 | 5572 | 5040 | 5357 | 5377 | 5659 | 5653 | 5739 | 5787 | 5554 | 5555 | 4670 | 4715 | 4687 | 4412 | 4432 | 4865 | 3975 | 3983 | 1930 | 1353 | 1045 | 1073 | 839 |
| Percentage of LiabilitiesNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 68.0 | 68.4 | 68.4 | 68.4 | 70.8 | 71.4 | 58.4 | 55.5 | 51.4 | 52.1 | 53.5 | 65.6 | 59.3 | 63.4 | 64.3 | 68.3 | 67.0 | 67.4 | 67.4 | 66.3 | 65.5 | 61.4 | 61.6 | 60.3 | 63.1 | 61.5 | 73.8 | 69.1 | 67.5 | 59.6 | 53.4 | 45.2 | 46.0 | 42.7 |
| Period End | 2020-12-31 | 2020-06-30 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 921 | 482 | 484 | 962 | 1003 |
| Percentage of LiabilitiesNoncurrent | 12.7 | 6.9 | 9.0 | 17.3 | 17.7 |
| Percentage of Assets | 8.7 | 5.0 | 5.0 | 11.3 | 12.1 |
| Percentage of Assets cwen:DesertSunlight | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 185 | 176 |
| Percentage of LiabilitiesNoncurrent | 2.6 | 3.3 |
| Percentage of Assets | 1.7 | 1.8 |
| Percentage of Assets cwen:GenConn | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 700 | 89 | 889 | 932 |
| Percentage of LiabilitiesNoncurrent | 9.7 | 1.7 | 16.0 | 16.5 |
| Percentage of Assets | 6.6 | 0.9 | 10.5 | 11.3 |
| Percentage of Assets cwen:InvestmentsOther | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2014-12-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2012-12-31 |
| Value | 7043 | 6858 | 6179 | 6184 | 5887 | 6044 | 5870 | 5970 | 6038 | 5914 | 5901 | 5983 | 6051 | 5770 | 5704 | 4772 | 4821 | 4863 | 4509 | 4069 | 1133 | 1167 | 1202 | 807 |
| Percentage of LongTermDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 66.5 | 70.7 | 69.9 | 70.8 | 69.5 | 71.1 | 69.1 | 70.7 | 72.2 | 71.4 | 69.9 | 70.3 | 70.5 | 68.8 | 67.2 | 62.7 | 62.9 | 62.5 | 64.5 | 70.7 | 49.0 | 50.1 | 58.0 | 41.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 7299 | 7434 | 7463 | 6585 | 6357 | 6377 | 5081 | 4956 | 4143 | 4192 | 4215 | 5447 | 4928 | 5244 | 5261 | 5531 | 5520 | 5597 | 5662 | 5426 | 5359 | 4465 | 4521 | 4562 | 4285 | 4336 | 4719 | 3890 | 3926 | 1880 | 1310 | 1000 | 1020 | 749 |
| Percentage of LongTermDebtNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 62.0 | 62.6 | 63.0 | 62.2 | 65.4 | 65.5 | 53.2 | 51.1 | 46.9 | 48.0 | 49.8 | 64.1 | 58.0 | 62.1 | 62.9 | 66.8 | 65.4 | 65.7 | 66.0 | 64.7 | 63.2 | 58.7 | 59.0 | 58.7 | 61.3 | 60.2 | 71.6 | 67.6 | 66.6 | 58.1 | 51.7 | 43.2 | 43.8 | 38.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-06-30 | 2012-12-31 |
| Value | 7299 | 7434 | 7463 | 6585 | 6357 | 6377 | 5081 | 4956 | 4143 | 4192 | 4225 | 5447 | 4928 | 5244 | 5261 | 5531 | 5520 | 5597 | 5662 | 5426 | 5359 | 4465 | 4521 | 4562 | 4285 | 4336 | 4719 | 3890 | 3926 | 1880 | 1310 | 1000 | 1076 | 749 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 62.0 | 62.6 | 63.0 | 62.2 | 65.4 | 65.5 | 53.2 | 51.1 | 46.9 | 48.0 | 49.9 | 64.1 | 58.0 | 62.1 | 62.9 | 66.8 | 65.4 | 65.7 | 66.0 | 64.7 | 63.2 | 58.7 | 59.0 | 58.7 | 61.3 | 60.2 | 71.6 | 67.6 | 66.6 | 58.1 | 51.7 | 43.2 | 51.9 | 38.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 1177 | 1209 | 1199 | 890 | 355 | 370 | 463 | 413 | 298 | 322 | 373 | 402 | 440 | 419 | 371 | 391 | 437 | 498 | 508 | 520 | 622 | 742 | 753 | 791 | 348 | 361 | 131 | 246 | 279 | 264 | 385 | 382 | 413 | 0.0 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Percentage of Assets | 10.0 | 10.2 | 10.1 | 8.4 | 3.7 | 3.8 | 4.8 | 4.3 | 3.4 | 3.7 | 4.4 | 4.7 | 5.2 | 5.0 | 4.4 | 4.7 | 5.2 | 5.8 | 5.9 | 6.2 | 7.3 | 9.8 | 9.8 | 10.2 | 5.0 | 5.0 | 2.0 | 4.3 | 4.7 | 8.2 | 15.2 | 16.5 | 17.7 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 890 | 413 | 402 | 412 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 | 105.4 |
| Percentage of Assets | 8.4 | 4.3 | 4.7 | 5.0 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 32.7 | 17.8 | 16.1 | 14.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 189 | 184 | 181 | 178 | 119 | 120 | 123 | 121 | 115 | 106 | 109 | 108 | 103 | 101 | 99 | 97 | 87 | 79 | 79 | 76 | 78 | 63 | 64 | 64 | 53 | 52 | 49 | 39 | 29 | 21 | 23 | 29 | 28 | 25 |
| Percentage of OtherLiabilitiesNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 1.6 | 1.5 | 1.5 | 1.7 | 1.2 | 1.2 | 1.3 | 1.2 | 1.3 | 1.2 | 1.3 | 1.3 | 1.2 | 1.2 | 1.2 | 1.2 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.8 | 0.8 | 0.7 | 0.7 | 0.7 | 0.5 | 0.6 | 0.9 | 1.3 | 1.2 | 1.3 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 5.0 | 6.0 | 5.0 | 6.0 |
| Percentage of OtherLiabilitiesNoncurrent | 2.8 | 5.0 | 4.6 | 6.2 |
| Percentage of Assets | 0.0 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 0.2 | 0.3 | 0.2 | 0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2018-12-31 |
| Value | 361 | 361 | 354 | 345 | 260 | 260 | 222 | 227 | 193 | 186 | 0.0 |
| Percentage of OperatingLeaseLiabilityNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Percentage of Assets | 3.1 | 3.0 | 3.0 | 3.3 | 2.7 | 2.7 | 2.3 | 2.3 | 2.2 | 2.1 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 23 | 18 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.2 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 23 | 18 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.2 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 23 | 18 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.2 |
| Period End | 2020-12-31 |
| Value | 23 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive | 100.0 |
| Percentage of Assets | 0.2 |
| Period End | 2020-12-31 |
| Value | 476 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive | 100.0 |
| Percentage of Assets | 4.5 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-01-01 |
| Value | 353 | 267 | 267 | 229 | 234 | 199 | 191 | 174 |
| Percentage of OperatingLeaseLiability | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 3.3 | 2.7 | 2.7 | 2.4 | 2.4 | 2.3 | 2.2 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-12-31 |
| Value | 20 | 20 | 20 | 21 |
| Percentage of OperatingLeaseLiability | 5.7 | 7.5 | 7.5 | 9.0 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 | 0.2 |
| Percentage of Assets cwen:OahuSolarPartnership | 0.0 | 0.0 | 0.0 | 9.8 |
| Period End | 2020-12-31 |
| Value | 12 |
| Percentage of OperatingLeaseLiability | 3.4 |
| Percentage of Assets | 0.1 |
| Percentage of Assets cwen:RosamondCentral | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 591 | 409 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDue | 100.0 | 100.0 |
| Percentage of Assets | 5.6 | 4.2 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 238 | 142 |
| Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount | 100.0 | 100.0 |
| Percentage of Assets | 2.2 | 1.5 |
| Period End | 2021-01-12 |
| Value | 107 |
| Percentage of StockholdersEquity | 100.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:ThirdPartyInvestor cwen:RattlesnakeTEHoldcoLLC us-gaap:CapitalUnitClassA | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-07-22 | 2013-06-30 | 2012-12-31 | 2011-12-31 | 2010-12-31 |
| Value | 2955 | 3003 | 2995 | 2715 | 2237 | 2232 | 2264 | 2263 | 2046 | 2054 | 2145 | 2224 | 2375 | 2287 | 2126 | 2138 | 2299 | 2336 | 2338 | 2370 | 2468 | 2557 | 2561 | 2632 | 2152 | 2206 | 1341 | 1480 | 1614 | 1073 | 1031 | 1011 | 991 | 788 | 0.0 | 0.0 | 561 | 193 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | 25.1 | 25.3 | 25.3 | 25.6 | 23.0 | 22.9 | 23.7 | 23.3 | 23.2 | 23.5 | 25.3 | 26.2 | 27.9 | 27.1 | 25.4 | 25.8 | 27.2 | 27.4 | 27.2 | 28.3 | 29.1 | 33.6 | 33.4 | 33.9 | 30.8 | 30.6 | 20.3 | 25.7 | 27.4 | 33.2 | 40.7 | 43.7 | 42.5 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 2715 | 2263 | 2224 | 2159 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 101.0 |
| Percentage of Assets | 25.6 | 23.3 | 26.2 | 26.1 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 99.8 | 97.8 | 89.0 | 77.7 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 |
| Value | -30.0 | -31.0 | -38.0 | -60.0 | -70.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -1.1 | -1.4 | -1.7 | -2.8 | -3.0 |
| Percentage of Assets | -0.3 | -0.3 | -0.4 | -0.7 | -0.8 |
| Percentage of Assets us-gaap:AccumulatedGainLossNetCashFlowHedgeParent | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2013-07-22 | 2012-12-31 | 2011-12-31 | 2010-12-31 |
| Value | -8.0 | -9.0 | -10.0 | -14.0 | -15.0 | -19.0 | -21.0 | -15.0 | -17.0 | -16.0 | -19.0 | -18.0 | -14.0 | -17.0 | -20.0 | -28.0 | -28.0 | -27.0 | -9.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.3 | -0.3 | -0.3 | -0.5 | -0.7 | -0.9 | -0.9 | -0.7 | -0.8 | -0.8 | -0.9 | -0.8 | -0.6 | -0.7 | -0.9 | -1.3 | -1.2 | -1.0 | -0.6 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | -0.1 | -0.1 | -0.1 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 | -0.3 | -0.3 | -0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2013-07-22 | 2012-12-31 | 2011-12-31 | 2010-12-31 |
| Value | 1810 | 1848 | 1886 | 1922 | 1918 | 1934 | 1922 | 1936 | 1830 | 1852 | 1870 | 1897 | 1935 | 1859 | 1827 | 1843 | 1879 | 1855 | 1240 | 621 | 0.0 | 840 | 0.0 | 0.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 61.3 | 61.5 | 63.0 | 70.8 | 85.7 | 86.6 | 84.9 | 85.6 | 89.4 | 90.2 | 87.2 | 85.3 | 81.5 | 81.3 | 85.9 | 86.2 | 79.3 | 70.5 | 83.8 | 61.4 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 15.4 | 15.6 | 15.9 | 18.1 | 19.7 | 19.9 | 20.1 | 20.0 | 20.7 | 21.2 | 22.1 | 22.3 | 22.8 | 22.0 | 21.8 | 22.3 | 22.4 | 23.9 | 21.6 | 26.8 | 0.0 | 42.8 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:AdditionalPaidInCapital | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | -16.0 | -19.0 | -19.0 | -30.0 | -31.0 | -39.0 | -43.0 | -31.0 | -36.0 | -35.0 | -40.0 | -38.0 | -30.0 | -36.0 | -43.0 | -60.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.5 | -0.6 | -0.6 | -1.1 | -1.4 | -1.7 | -1.9 | -1.4 | -1.8 | -1.7 | -1.9 | -1.7 | -1.3 | -1.6 | -2.0 | -2.8 |
| Percentage of Assets | -0.1 | -0.2 | -0.2 | -0.3 | -0.3 | -0.4 | -0.5 | -0.3 | -0.4 | -0.4 | -0.5 | -0.4 | -0.4 | -0.4 | -0.5 | -0.7 |
| Percentage of Assets us-gaap:AociIncludingPortionAttributableToNoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2013-07-22 | 2012-12-31 | 2011-12-31 | 2010-12-31 |
| Value | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:CommonStock | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2013-07-22 | 2012-12-31 | 2011-12-31 | 2010-12-31 |
| Value | 1177 | 1209 | 1199 | 890 | 355 | 370 | 463 | 413 | 298 | 322 | 373 | 402 | 440 | 419 | 371 | 391 | 520 | 791 | 246 | 382 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 39.8 | 40.3 | 40.0 | 32.8 | 15.9 | 16.6 | 20.5 | 18.3 | 14.6 | 15.7 | 17.4 | 18.1 | 18.5 | 18.3 | 17.5 | 18.3 | 21.9 | 30.1 | 16.6 | 37.8 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 10.0 | 10.2 | 10.1 | 8.4 | 3.7 | 3.8 | 4.8 | 4.3 | 3.4 | 3.7 | 4.4 | 4.7 | 5.2 | 5.0 | 4.4 | 4.7 | 6.2 | 10.2 | 4.3 | 16.5 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2013-07-22 | 2012-12-31 | 2011-12-31 |
| Value | -25.0 | -46.0 | -81.0 | -84.0 | -22.0 | -54.0 | -101.0 | -72.0 | -66.0 | -105.0 | -80.0 | -58.0 | 13 | 26 | -53.0 | -69.0 | -2.0 | 12 | 3.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.8 | -1.5 | -2.7 | -3.1 | -1.0 | -2.4 | -4.5 | -3.2 | -3.2 | -5.1 | -3.7 | -2.6 | 0.5 | 1.1 | -2.5 | -3.2 | -0.1 | 0.5 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | -0.2 | -0.4 | -0.7 | -0.8 | -0.2 | -0.6 | -1.1 | -0.7 | -0.7 | -1.2 | -0.9 | -0.7 | 0.2 | 0.3 | -0.6 | -0.8 | -0.0 | 0.2 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:RetainedEarnings | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2014-12-31 | 2013-06-30 | 2012-12-31 |
| Value | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 10.0 | 10.0 |
| Percentage of CommonStockValue | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2013-12-31 |
| Value | 1810 | 1848 | 1886 | 1922 | 1918 | 1934 | 1922 | 1936 | 1830 | 1852 | 1870 | 1897 | 1935 | 1859 | 1827 | 1843 | 1864 | 1842 | 1859 | 1879 | 1858 | 1835 | 1844 | 1855 | 1820 | 1852 | 1235 | 1240 | 621 |
| Percentage of AdditionalPaidInCapital | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 15.4 | 15.6 | 15.9 | 18.1 | 19.7 | 19.9 | 20.1 | 20.0 | 20.7 | 21.2 | 22.1 | 22.3 | 22.8 | 22.0 | 21.8 | 22.3 | 22.1 | 21.6 | 21.7 | 22.4 | 21.9 | 24.1 | 24.1 | 23.9 | 26.0 | 25.7 | 18.7 | 21.6 | 26.8 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 1922 | 1936 | 1897 | 1843 |
| Percentage of AdditionalPaidInCapital | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 18.1 | 20.0 | 22.3 | 22.3 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 70.7 | 83.7 | 75.9 | 66.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | -25.0 | -46.0 | -81.0 | -84.0 | -22.0 | -54.0 | -101.0 | -72.0 | -66.0 | -105.0 | -80.0 | -58.0 | 13 | 25 | -53.0 | -69.0 | 24 | 23 | -5.0 | -2.0 | 35 | 26 | 7.0 | 12 | 15 | 8.0 | -2.0 | 3.0 | 5.0 | 3.0 | 4.0 | 8.0 | 9.0 | 30 |
| Percentage of RetainedEarningsAccumulatedDeficit | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | -0.2 | -0.4 | -0.7 | -0.8 | -0.2 | -0.6 | -1.1 | -0.7 | -0.7 | -1.2 | -0.9 | -0.7 | 0.2 | 0.3 | -0.6 | -0.8 | 0.3 | 0.3 | -0.1 | -0.0 | 0.4 | 0.3 | 0.1 | 0.2 | 0.2 | 0.1 | -0.0 | 0.1 | 0.1 | 0.1 | 0.2 | 0.3 | 0.4 | 1.5 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | -84.0 | -72.0 | -58.0 | -69.0 |
| Percentage of RetainedEarningsAccumulatedDeficit | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | -0.8 | -0.7 | -0.7 | -0.8 |
| Percentage of Assets cwen:ClearwayEnergyInc. | -3.1 | -3.1 | -2.3 | -2.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | -8000000.0 | -9000000.0 | -10000000.0 | -14000000.0 | -15000000.0 | -19000000.0 | -21000000.0 | -15000000.0 | -17000000.0 | -16000000.0 | -19000000.0 | -18000000.0 | -14000000.0 | -17000000.0 | -20000000.0 | -28000000.0 | -27000000.0 | -28000000.0 | -25000000.0 | -28000000.0 | -48000000.0 | -47000000.0 | -44000000.0 | -27000000.0 | -32000000.0 | -16000000.0 | -23000000.0 | -9000000.0 | -6000000.0 | -9000000.0 | -2000000.0 | 0 | -2000000.0 | -24000000.0 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | -0.1 | -0.1 | -0.1 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 | -0.3 | -0.3 | -0.3 | -0.3 | -0.6 | -0.6 | -0.6 | -0.3 | -0.5 | -0.2 | -0.3 | -0.2 | -0.1 | -0.3 | -0.1 | 0.0 | -0.1 | -1.2 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | -14000000.0 | -15000000.0 | -18000000.0 | -28000000.0 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | -0.1 | -0.2 | -0.2 | -0.3 |
| Percentage of Assets cwen:ClearwayEnergyInc. | -0.5 | -0.6 | -0.7 | -1.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-06-30 | 2017-12-31 |
| Value | -8000000.0 | -9000000.0 | -10000000.0 | -14000000.0 | -15000000.0 | -19000000.0 | -21000000.0 | -15000000.0 | -17000000.0 | -16000000.0 | -19000000.0 | -18000000.0 | -17000000.0 | -28000000.0 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | -0.1 | -0.1 | -0.1 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 |
| Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -8000000.0 | -10000000.0 | -9000000.0 | -16000000.0 | -20000000.0 | -22000000.0 | -19000000.0 | -19000000.0 | -21000000.0 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax | 100.0 | 111.1 | 90.0 | 106.7 | 105.3 | 104.8 | 111.8 | 118.8 | 110.5 |
| Percentage of Assets | -0.1 | -0.1 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 |
| Percentage of Assets us-gaap:AociAttributableToNoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2016-12-31 | 2016-09-30 | 2016-06-30 |
| Value | -16000000.0 | -16000000.0 | -19000000.0 | -19000000.0 | -21000000.0 | -20000000.0 | -16000000.0 | -19000000.0 | -23000000.0 | -32000000.0 | -36000000.0 | -42000000.0 | -42000000.0 | -71000000.0 | -42000000.0 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax | 114.3 | 106.7 | 111.8 | 118.8 | 110.5 | 111.1 | 114.3 | 111.8 | 115.0 | 114.3 | 133.3 | 150.0 | 150.0 | 147.9 | 89.4 |
| Percentage of Assets | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 | -0.4 | -0.4 | -0.5 | -0.5 | -0.8 | -0.6 |
| Percentage of Assets us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2012-12-31 |
| Value | 1177 | 1209 | 1199 | 890 | 355 | 370 | 463 | 413 | 298 | 322 | 373 | 402 | 440 | 419 | 371 | 391 | 437 | 498 | 508 | 520 | 622 | 742 | 753 | 791 | 348 | 361 | 131 | 246 | 279 | 264 | 385 | 382 | 413 | 0.0 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Percentage of Assets | 10.0 | 10.2 | 10.1 | 8.4 | 3.7 | 3.8 | 4.8 | 4.3 | 3.4 | 3.7 | 4.4 | 4.7 | 5.2 | 5.0 | 4.4 | 4.7 | 5.2 | 5.8 | 5.9 | 6.2 | 7.3 | 9.8 | 9.8 | 10.2 | 5.0 | 5.0 | 2.0 | 4.3 | 4.7 | 8.2 | 15.2 | 16.5 | 17.7 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 890 | 413 | 402 | 412 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 | 105.4 |
| Percentage of Assets | 8.4 | 4.3 | 4.7 | 5.0 |
| Percentage of Assets cwen:ClearwayEnergyInc. | 32.7 | 17.8 | 16.1 | 14.8 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 20 | 28 | 10.0 | 76 | 65 | 10.0 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 20 | 28 | 10.0 | 76 | 65 | 10.0 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:AdditionalPaidInCapital | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 |
| Value | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 0 | 1000000.0 | 1000000.0 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 |
| Value | 11 | 6.0 | 3.0 | 4.0 | 30 |
| Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-01 |
| Value | 9.0 |
| Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:UtahSolarHoldingsLLC cwen:ClearwayEnergyOperatingLLC cwen:UtahSolarHoldingsDue2036 us-gaap:NotesPayableOtherPayables srt:AffiliatedEntity | 0.0 |
| Period End | 2020-09-30 |
| Value | 45 |
| Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders | 750.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets cwen:ClearwayEnergyOperatingLLC cwen:NIMHSolarLLCFinancingArrangement us-gaap:LoansPayable srt:AffiliatedEntity | 0.0 |
| Period End | 2021-09-30 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 |
| Value | 11 | 6.0 | 3.0 | 4.0 | 30 |
| Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 288 | 194 | 47 | 104 | 257 | 100 | 84 | 103 | 224 | 89 | 61 | 102 | 215 | 116 | 65 | 142 | 203 | 110 | 61 | 121 | 241 | 96 | 102 | 104 | 181 | 10.0 | 78 | 29 | 121 | 57 | 16 | 38 | 122 | -29.0 | 10.0 | 38 |
| Percentage of NetCashProvidedByUsedInOperatingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 82.1 | 51.1 | 19.8 | 37.1 | 77.4 | 30.4 | 152.7 | 43.8 | 350.0 | 156.1 | 110.9 | 44.5 | 341.3 | 200.0 | 106.6 | 61.5 | 76.6 | 38.7 | 28.0 | 52.2 | 88.6 | 37.2 | 46.4 | 49.8 | 86.6 | 4.6 | 43.3 | 19.6 | 75.2 | 42.5 | 14.5 | 44.2 | 128.4 | -36.7 | 18.9 | 90.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | -10.0 | -106.0 | -314.0 | -42.0 | -60.0 | 57 | -17.0 | -168.0 | -89.0 | -185.0 | -26.0 | -10.0 | -9.0 | -122.0 | -44.0 | -79.0 | -61.0 | -80.0 | -63.0 | -19.0 | -100.0 | 16 | -58.0 | -222.0 | -59.0 | -348.0 | -489.0 | 53 | -917.0 | -331.0 | 127 | -95.0 | 18 | -129.0 | -182.0 | -143.0 |
| Percentage of NetCashProvidedByUsedInInvestingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -2.8 | -27.9 | -132.5 | -15.0 | -18.1 | 17.3 | -30.9 | -71.5 | -139.1 | -324.6 | -47.3 | -4.4 | -14.3 | -210.3 | -72.1 | -34.2 | -23.0 | -28.2 | -28.9 | -8.2 | -36.8 | 6.2 | -26.4 | -106.2 | -28.2 | -160.4 | -271.7 | 35.8 | -569.6 | -247.0 | 115.5 | -110.5 | 18.9 | -163.3 | -343.4 | -340.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | -193.0 | -49.0 | 233 | -134.0 | -76.0 | -121.0 | -104.0 | 85 | -34.0 | 94 | -320.0 | 102 | -86.0 | -2.0 | -60.0 | -77.0 | -118.0 | -113.0 | -107.0 | 15 | -30.0 | -99.0 | -79.0 | 81 | -278.0 | 505 | 119 | -63.0 | 1081 | -82.0 | 241 | -28.0 | -37.0 | 153 | 173 | 97 |
| Percentage of NetCashProvidedByUsedInFinancingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -55.0 | -12.9 | 98.3 | -47.9 | -22.9 | -36.8 | -189.1 | 36.2 | -53.1 | 164.9 | -581.8 | 44.5 | -136.5 | -3.4 | -98.4 | -33.3 | -44.5 | -39.8 | -49.1 | 6.5 | -11.0 | -38.4 | -35.9 | 38.8 | -133.0 | 232.7 | 66.1 | -42.6 | 671.4 | -61.2 | 219.1 | -32.6 | -38.9 | 193.7 | 326.4 | 231.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 85 | 39 | -34.0 | -72.0 | 121 | 36 | -37.0 | 20 | 101 | -2.0 | -285.0 | 194 | 120 |
| Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 24.2 | 10.3 | -14.3 | -25.7 | 36.4 | 10.9 | -67.3 | 8.5 | 157.8 | -3.5 | -518.2 | 84.7 | 190.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 |
| Value | 131 | 128 | 128 | 125 | 102 | 99 | 102 | 111 | 112 | 89 | 84 | 84 | 84 | 82 | 81 | 93 | 88 | 78 | 75 | 73 | 75 | 67 | 66 | 102 | 50 | 59 | 54 | 42 | 34 | 36 | 17 | 16 | 16 | 9.0 | 10.0 | 7.0 | 6.0 | 6.0 |
| Percentage of DepreciationDepletionAndAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 34 | 31 | 34 | 32 | 34 | 33 | 33 | 27 | 25 | 25 | 25 | 25 | 26 |
| Percentage of DepreciationDepletionAndAmortization | 26.0 | 24.2 | 26.6 | 25.6 | 33.3 | 33.3 | 32.4 | 24.3 | 22.3 | 28.1 | 29.8 | 29.8 | 31.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 90 | 89 | 87 | 82 | 61 | 59 | 62 | 77 | 80 | 58 | 54 | 53 | 52 |
| Percentage of DepreciationDepletionAndAmortization | 68.7 | 69.5 | 68.0 | 65.6 | 59.8 | 59.6 | 60.8 | 69.4 | 71.4 | 65.2 | 64.3 | 63.1 | 61.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 7.0 | 8.0 | 7.0 | 11 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 6.0 | 6.0 | 6.0 |
| Percentage of DepreciationDepletionAndAmortization | 5.3 | 6.2 | 5.5 | 8.8 | 6.9 | 7.1 | 6.9 | 6.3 | 6.2 | 7.9 | 7.1 | 7.1 | 7.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 27 | 27 | 3.0 | 16 | 3.0 | 48 | -22.0 | -33.0 | 11 | 34 | -7.0 | -14.0 | 8.0 | 45 | -9.0 | -31.0 | 21 | 24 | -8.0 | -14.0 | 11 | -17.0 | 13 | 11 | -61.0 | 67 | 5.0 | -3.0 | -16.0 | 25 | 25 | 2.0 | -79.0 | 73 | 7.0 | -27.0 |
| Percentage of IncreaseDecreaseInOtherOperatingCapitalNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 288 | 194 | 47 | 104 | 257 | 100 | 84 | 103 | 224 | 89 | 61 | 102 | 215 | 116 | 65 | 142 | 203 | 110 | 61 | 121 | 241 | 96 | 102 | 104 | 181 | 10.0 | 78 | 29 | 121 | 57 | 16 | 38 | 122 | -29.0 | 10.0 | 38 |
| Percentage of NetCashProvidedByUsedInOperatingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 82.1 | 51.1 | 19.8 | 37.1 | 77.4 | 30.4 | 152.7 | 43.8 | 350.0 | 156.1 | 110.9 | 44.5 | 341.3 | 200.0 | 106.6 | 61.5 | 76.6 | 38.7 | 28.0 | 52.2 | 88.6 | 37.2 | 46.4 | 49.8 | 86.6 | 4.6 | 43.3 | 19.6 | 75.2 | 42.5 | 14.5 | 44.2 | 128.4 | -36.7 | 18.9 | 90.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2014-09-30 | 2014-06-30 | 2013-09-30 | 2013-06-30 | 2012-06-30 |
| Value | 21 | 35 | 3.0 | -25.0 | 32 | 47 | -29.0 | -6.0 | 39 | -24.0 | -20.0 | 6.0 | 6.0 | 9.0 | 33 | -1.0 |
| Percentage of NetIncomeLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.0 | 9.2 | 1.3 | -8.9 | 9.6 | 14.3 | -52.7 | -2.6 | 60.9 | -42.1 | -36.4 | 3.7 | 4.5 | 9.5 | 41.8 | -2.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 6.0 | 10.0 | 1.0 | 9.0 | 14 | -9.0 | 12 | -8.0 | -6.0 |
| Percentage of NetIncomeLoss | 28.6 | 28.6 | 33.3 | 28.1 | 29.8 | 31.0 | 30.8 | 33.3 | 30.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | 2.6 | 0.4 | 2.7 | 4.3 | -16.4 | 18.8 | -14.0 | -10.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 15 | 25 | 2.0 | 22 | 33 | -20.0 | 27 | -16.0 | -14.0 |
| Percentage of NetIncomeLoss | 71.4 | 71.4 | 66.7 | 68.8 | 70.2 | 69.0 | 69.2 | 66.7 | 70.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.3 | 6.6 | 0.8 | 6.6 | 10.0 | -36.4 | 42.2 | -28.1 | -25.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommonClassC | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 | 2012-03-31 |
| Value | 25 | 32 | -76.0 | -73.0 | 42 | 76 | -107.0 | -48.0 | 35 | -36.0 | -47.0 | -91.0 | 49 | 96 | 0.0 | -98.0 | 41 | 45 | -1.0 | -126.0 | 47 | 58 | 2.0 | 13 | 34 | 41 | -16.0 | -10.0 | 31 | 34 | 18 | 24 | 40 | 34 | 11 | 5.0 | 4.0 | -1.0 | 5.0 |
| Percentage of ProfitLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 7.1 | 8.4 | -32.1 | -26.1 | 12.7 | 23.1 | -194.5 | -20.4 | 54.7 | -63.2 | -85.5 | -39.7 | 77.8 | 165.5 | 0.0 | -42.4 | 15.5 | 15.8 | -0.5 | -54.3 | 17.3 | 22.5 | 0.9 | 6.2 | 16.3 | 18.9 | -8.9 | -6.8 | 19.3 | 25.4 | 16.4 | 27.9 | 42.1 | 43.0 | 20.8 | 11.9 | 8.5 | -2.4 | 11.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -37.0 | -41.0 | -57.0 | -32.0 | -41.0 | -10.0 | -13.0 | -52.0 | -17.0 | -33.0 | -20.0 | -79.0 | -55.0 |
| Percentage of ProfitLoss | -148.0 | -128.1 | 75.0 | 43.8 | -97.6 | -13.2 | 12.1 | 108.3 | -48.6 | 91.7 | 42.6 | 86.8 | -112.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -10.5 | -10.8 | -24.1 | -11.4 | -12.3 | -3.0 | -23.6 | -22.1 | -26.6 | -57.9 | -36.4 | -34.5 | -87.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 52 | 40 | 33 | 43 | 48 | 31 | 18 | 38 | 41 | 32 | 24 | 28 | 39 |
| Percentage of ProfitLoss | 208.0 | 125.0 | -43.4 | -58.9 | 114.3 | 40.8 | -16.8 | -79.2 | 117.1 | -88.9 | -51.1 | -30.8 | 79.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 14.8 | 10.5 | 13.9 | 15.4 | 14.5 | 9.4 | 32.7 | 16.2 | 64.1 | 56.1 | 43.6 | 12.2 | 61.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:ConventionalGeneration | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 6.0 | 27 | -56.0 | -83.0 | 34 | 54 | -114.0 | -34.0 | 6.0 | -20.0 | -56.0 | -45.0 | 55 |
| Percentage of ProfitLoss | 24.0 | 84.4 | 73.7 | 113.7 | 81.0 | 71.1 | 106.5 | 70.8 | 17.1 | 55.6 | 119.1 | 49.5 | 112.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.7 | 7.1 | -23.6 | -29.6 | 10.2 | 16.4 | -207.3 | -14.5 | 9.4 | -35.1 | -101.8 | -19.7 | 87.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Renewables | 12.5 | 49.1 | 560.0 | -307.4 | 178.9 | 300.0 | -1628.6 | -566.7 | 66.7 | -181.8 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 4.0 | 6.0 | 4.0 | -1.0 | 1.0 | 1.0 | 2.0 | 0.0 | 5.0 | -15.0 | 5.0 | 5.0 | 10.0 |
| Percentage of ProfitLoss | 16.0 | 18.8 | -5.3 | 1.4 | 2.4 | 1.3 | -1.9 | -0.0 | 14.3 | 41.7 | -10.6 | -5.5 | 20.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.1 | 1.6 | 1.7 | -0.4 | 0.3 | 0.3 | 3.6 | 0.0 | 7.8 | -26.3 | 9.1 | 2.2 | 15.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments cwen:Thermal | 7.4 | 12.0 | 8.2 | -2.3 | 1.7 | 2.4 | 4.2 | 0.0 | 9.1 | -32.6 | 10.0 | 10.4 | 18.9 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 0.0 | 4.0 | -16.0 | 16 | 9.0 | 1.0 |
| Percentage of ProfitLoss | 0.0 | 5.3 | 15.0 | 45.7 | -25.0 | -2.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 1.2 | -29.1 | 25.0 | 15.8 | 1.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax cwen:DGPVHoldco3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 3.0 | -4.0 | -81.0 | 10.0 | 29 | -78.0 | -4.0 | -12.0 | -27.0 | 28 | 17 | -20.0 |
| Percentage of ProfitLoss | 12.0 | -12.5 | 106.6 | 23.8 | 38.2 | 72.9 | -11.4 | 33.3 | 57.4 | 57.1 | 17.7 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | -1.1 | -34.2 | 3.0 | 8.8 | -141.8 | -6.2 | -21.1 | -49.1 | 44.4 | 29.3 | -32.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 21 | 35 | 3.0 | 14 | 32 | 47 | -29.0 | 39 | -24.0 | -20.0 | 21 | 79 | 16 |
| Percentage of ProfitLoss | 84.0 | 109.4 | -3.9 | -19.2 | 76.2 | 61.8 | 27.1 | 111.4 | 66.7 | 42.6 | 42.9 | 82.3 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.0 | 9.2 | 1.3 | 5.0 | 9.6 | 14.3 | -52.7 | 60.9 | -42.1 | -36.4 | 33.3 | 136.2 | 26.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | -10.0 | -106.0 | -314.0 | -42.0 | -60.0 | 57 | -17.0 | -168.0 | -89.0 | -185.0 | -26.0 | -10.0 | -9.0 | -122.0 | -44.0 | -79.0 | -61.0 | -80.0 | -63.0 | -19.0 | -100.0 | 16 | -58.0 | -222.0 | -59.0 | -348.0 | -489.0 | 53 | -917.0 | -331.0 | 127 | -95.0 | 18 | -129.0 | -182.0 | -143.0 |
| Percentage of NetCashProvidedByUsedInInvestingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -2.8 | -27.9 | -132.5 | -15.0 | -18.1 | 17.3 | -30.9 | -71.5 | -139.1 | -324.6 | -47.3 | -4.4 | -14.3 | -210.3 | -72.1 | -34.2 | -23.0 | -28.2 | -28.9 | -8.2 | -36.8 | 6.2 | -26.4 | -106.2 | -28.2 | -160.4 | -271.7 | 35.8 | -569.6 | -247.0 | 115.5 | -110.5 | 18.9 | -163.3 | -343.4 | -340.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 31 | 14 | 79 | 29 | 12 | 43 | 40 | 28 | 104 | 80 | 16 | 21 | 17 | 27 | 18 | 8.0 | 10.0 | 9.0 | 4.0 | 4.0 | 5.0 | 4.0 | 7.0 | 13 | 8.0 | 5.0 | 3.0 | 5.0 | -1.0 | 10.0 | 19 | 6.0 | -35.0 | 88 | 179 | 107 |
| Percentage of PaymentsToAcquirePropertyPlantAndEquipment | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-04-23 |
| Value | 100 |
| Percentage of PaymentsToAcquireProductiveAssets | 100.0 |
| Period End | 2021-03-10 |
| Value | 21 |
| Percentage of PaymentsToAcquireProductiveAssets | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | -193.0 | -49.0 | 233 | -134.0 | -76.0 | -121.0 | -104.0 | 85 | -34.0 | 94 | -320.0 | 102 | -86.0 | -2.0 | -60.0 | -77.0 | -118.0 | -113.0 | -107.0 | 15 | -30.0 | -99.0 | -79.0 | 81 | -278.0 | 505 | 119 | -63.0 | 1081 | -82.0 | 241 | -28.0 | -37.0 | 153 | 173 | 97 |
| Percentage of NetCashProvidedByUsedInFinancingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -55.0 | -12.9 | 98.3 | -47.9 | -22.9 | -36.8 | -189.1 | 36.2 | -53.1 | 164.9 | -581.8 | 44.5 | -136.5 | -3.4 | -98.4 | -33.3 | -44.5 | -39.8 | -49.1 | 6.5 | -11.0 | -38.4 | -35.9 | 38.8 | -133.0 | 232.7 | 66.1 | -42.6 | 671.4 | -61.2 | 219.1 | -32.6 | -38.9 | 193.7 | 326.4 | 231.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 21 | 12 | 1004 | 309 | 489 | 255 | 31 | 629 | 93 | 489 | 4.0 | 600 | 0.0 | 213 | 14 | 0.0 | 0.0 | 0.0 | 41 | 125 | 550 | 0.0 | 0.0 | 255 | 14 | 365 | 210 | 0.0 | 538 | 41 | 345 | 0.0 | -99.0 | 163 | 356 | 68 |
| Percentage of ProceedsFromIssuanceOfLongTermDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 |
| Value | 142 | 71 | 957 | 473 | 507 | 110 | 437 | 784 | 84 | 312 | 304 | 425 | 100 | 206 | 79 | 108 | 82 | 67 | 75 | 60 | 82 | 55 | 67 | 55 |
| Percentage of RepaymentsOfLongTermDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 |
| Value | 3.8 | 17.9 | 20.8 | -69.0 | 17.6 | 0.255 | 0.171 | -0.149 | -0.46 | -0.125 | 0.13 | 0.425 | 0.183 | 0.068 | 1.0 | 1.32 | 0.163 | 0.151 | 0.5 | -0.12082 | 0.21667 | 0.17143 | 0 | 0.059597 | 0.19048 | 0.088889 | 0.2 | -0.095 | 0.244 | 0.056 | 0.143 | 0.012 | 0.111 | 0.029 | 0 | -0.121 | 0.667 | 0.5 |
| Percentage of EffectiveIncomeTaxRateContinuingOperations | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 |
| Value | 330 | 319 | 249 | 198 | 219 | 197 |
| Percentage of DeferredTaxAssetsNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 |
| Value | 15 | 15 | 15 | 10.0 | 16 | 0.0 |
| Percentage of DeferredTaxAssetsValuationAllowance | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 2.0 | 3.0 | 27 | -1.0 | 8.0 | 1.0 | 6.0 | 12 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalDistributionsPaidNonCashNetOfContributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-10 |
| Value | 27 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalDistributionsPaidNonCashNetOfContributions | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 2.0 | 3.0 | 27 | -1.0 | 8.0 | 1.0 | 6.0 | 12 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalDistributionsPaidNonCashNetOfContributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 37 | 38 | 32 | 23 | 22 | 23 | 22 | 19 | 17 | 18 | 17 | 18 | 17 | 18 | 17 | 18 |
| Percentage of AmortizationOfIntangiblesAndOutOfMarketContracts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 5000000.0 |
| Percentage of AssetAcquisitionAccountPayableAndOtherCurrentLiabilities | 100.0 |
| Period End | 2021-04-23 |
| Value | 4000000.0 |
| Percentage of AssetAcquisitionAccountPayableAndOtherCurrentLiabilities | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 0 | 1000000.0 |
| Percentage of AssetAcquisitionAcquisitionRelatedCosts | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 0 | 1000000.0 |
| Percentage of AssetAcquisitionAcquisitionRelatedCosts | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 1276 |
| Percentage of AssetAcquisitionAssetsAcquired | 100.0 |
| Period End | 2021-04-23 |
| Value | 113 |
| Percentage of AssetAcquisitionAssetsAcquired | 0.0 |
| Period End | 2021-01-12 |
| Value | 220 |
| Percentage of AssetAcquisitionAssetsAcquired | 0.0 |
| Period End | 2021-02-03 |
| Value | 202 |
| Percentage of AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet | 100.0 |
| Period End | 2021-04-23 |
| Value | 100 |
| Percentage of AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet | 0.0 |
| Period End | 2021-01-12 |
| Value | 14 |
| Percentage of AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet | 0.0 |
| Period End | 2021-02-03 |
| Value | 91 |
| Percentage of AssetAcquisitionCashAndCashEquivalentsAndRestrictedCash | 100.0 |
| Period End | 2021-04-23 |
| Value | 96 |
| Percentage of AssetAcquisitionConsiderationGross | 100.0 |
| Period End | 2021-04-23 |
| Value | 4000000.0 |
| Percentage of AssetAcquisitionConsiderationTransferredWorkingCapitalAndPurchasePriceAdjustments | 100.0 |
| Period End | 2021-04-23 |
| Value | 3000000.0 |
| Percentage of AssetAcquisitionCurrentAssets | 100.0 |
| Period End | 2021-01-12 |
| Value | 8000000.0 |
| Percentage of AssetAcquisitionCurrentAssets | 0.0 |
| Period End | 2021-04-23 |
| Value | 9000000.0 |
| Percentage of AssetAcquisitionDerivativeInstrumentNotionalAmount | 100.0 |
| Period End | 2021-02-03 |
| Value | -80000000.0 |
| Percentage of AssetAcquisitionEquityMethodInvestmentRemoved | 100.0 |
| Period End | 2021-01-12 |
| Value | 12 |
| Percentage of AssetAcquisitionLeaseLiabilitiesNoncurrent | 100.0 |
| Period End | 2021-02-03 |
| Value | 721 |
| Percentage of AssetAcquisitionLiabilitiesAssumed | 100.0 |
| Period End | 2021-04-23 |
| Value | 13 |
| Percentage of AssetAcquisitionLiabilitiesAssumed | 0.0 |
| Period End | 2021-01-12 |
| Value | 206 |
| Percentage of AssetAcquisitionLiabilitiesAssumed | 0.0 |
| Period End | 2021-01-12 |
| Value | 18 |
| Percentage of AssetAcquisitionLiabilitiesOtherCurrentAndNoncurrent | 100.0 |
| Period End | 2021-02-03 |
| Value | 716 |
| Percentage of AssetAcquisitionLongTermDebt | 100.0 |
| Period End | 2021-01-12 |
| Value | 176 |
| Percentage of AssetAcquisitionLongTermDebt | 0.0 |
| Period End | 2021-02-03 |
| Value | 273 |
| Percentage of AssetAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue | 100.0 |
| Period End | 2021-02-03 |
| Value | 9000000.0 |
| Percentage of AssetAcquisitionOtherAssetsCurrent | 100.0 |
| Period End | 2021-02-03 |
| Value | 91 |
| Percentage of AssetAcquisitionRestrictedCash | 100.0 |
| Period End | 2021-01-12 |
| Value | 12 |
| Percentage of AssetAcquisitionRightOfUseAsset | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | -96.0 | 32 | 44 | 16 | -92.0 | 32 | 45 | 11 | -72.0 | 25 | 35 | 8.0 | -70.0 | 26 | 36 | 9.0 |
| Percentage of ChangesinPrepaidandAccruedCapacityPayments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 |
| Value | 0 |
| Percentage of GainLossOnExtinguishmentOfDeferredFinancingFees | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0 | 0 | 54.93 | 54.391 | -0.0001 | 0.5495 |
| Percentage of LimitedLiabilityCompanyLLCorLimitedPartnershipLPMembersorLimitedPartnersVotingInterest | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0 | 0 | 45.07 | 44.609 | 0.0001 | 0.4505 |
| Percentage of LimitedLiabilityCompanyLLCorLimitedPartnershipLPMembersorLimitedPartnersVotingInterest | 0.0 | 0.0 | 82.0 | 82.0 | -100.0 | 82.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 24 | 31 | -78.0 |
| Percentage of NetIncomeLossIncludingPortionAttributableToNoncontrollingInterestIncludingRoundingAdjustments | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-01 |
| Value | 83 |
| Percentage of NoncontrollingInterestAdjustmentForPurchaseOfInterests | 100.0 |
| Period End | 2020-11-02 |
| Value | 144 |
| Percentage of NoncontrollingInterestAdjustmentForPurchaseOfInterests | 0.0 |
| Period End | 2020-09-01 |
| Value | 83 |
| Percentage of NoncontrollingInterestAdjustmentForPurchaseOfInterests | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 6.0 | 3.0 |
| Percentage of NoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHoldersCash | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 6.0 | 3.0 |
| Percentage of NoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHoldersCash | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 3000000.0 | 3000000.0 | 2000000.0 | 3000000.0 | 2000000.0 | -3000000.0 | 2000000.0 | 2000000.0 | 2000000.0 | 3000000.0 | 0 |
| Percentage of OperatingLeaseRightofUseAssetAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 100 | 111 |
| Percentage of PaymentsForAssetAcquisition | 0.0 | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 202 |
| Percentage of PaymentsForAssetAcquisition | 0.0 |
| Period End | 2021-01-12 |
| Value | 132 |
| Percentage of PaymentsForAssetAcquisition | 0.0 |
| Period End | 2021-02-03 |
| Value | 111 |
| Percentage of PaymentsForAssetAcquisitionNetCashOutflow | 100.0 |
| Period End | 2021-09-30 |
| Value | 0.0 |
| Percentage of PaymentsToAcquireAssetsFromAffiliate | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 0.0 | 132 |
| Percentage of PaymentsToAcquireBusinessTwo | 0.0 | 0.0 | 100.0 |
| Period End | 2021-01-12 |
| Value | 29 |
| Percentage of PaymentsToFundProjectReserveAccounts | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 43 | 155 | 6.0 | 0.0 | 0.0 | 0.0 | 0.0 | 84 | 42 | 74 |
| Percentage of PaymenttoAcquireBusinessunderCommonControl | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 154 |
| Percentage of PropertyPlantAndEquipmentAdditionsNet | 100.0 |
| Period End | 2021-04-23 |
| Value | 108 |
| Percentage of PropertyPlantAndEquipmentAdditionsNet | 0.0 |
| Period End | 2021-01-12 |
| Value | 200 |
| Percentage of PropertyPlantAndEquipmentAdditionsNet | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 35 | 31 | 24 | 0.0 | 3.0 | 5.0 | 0.0 | 2.0 | 0.0 | 7.0 |
| Percentage of RevenueMarktomarketHedgingActivities | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 35 | 31 | 24 | 0.0 | 3.0 | 5.0 | 0.0 | 2.0 | 0.0 | 7.0 |
| Percentage of RevenueMarktomarketHedgingActivities | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 0 | 200000.0 |
| Percentage of SaleOfStockCommissionFees | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2015-12-31 |
| Value | -1.0 | 2.0 | 20 | 7.0 | -1.0 | 2.0 | -1.0 | 0.0 | 3.0 | 9.0 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalOther | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2019-09-30 | 2019-06-30 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | -1.0 | 2.0 | 20 | 7.0 | -1.0 | 2.0 | -1.0 | -2.0 | 3.0 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalOther | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 3.0 | 3.0 | 4.0 | 3.0 | 4.0 | 4.0 | 4.0 | 3.0 | 7.0 | 3.0 | 4.0 | 5.0 | 6.0 | 6.0 | 7.0 | 7.0 | 7.0 | 6.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 3.0 | 3.0 | 2.0 | 3.0 | 4.0 | 1.0 | 1.0 | 0.0 | 0.0 | 1.0 | 0.0 |
| Percentage of AmortizationOfFinancingCostsAndDiscounts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2014-12-31 | 2014-09-30 | 2013-12-31 | 2013-09-30 |
| Value | 1.0 | 1.0 | 2.0 | 7.0 | 1.0 | 0.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 17 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 0.0 | 0.0 | 0.0 | 1.0 | 1.0 | 1.0 | 2.0 | 2.0 | 0.0 | 0.0 |
| Percentage of BusinessCombinationAcquisitionRelatedCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 7.0 | 1.0 | 0.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 17 |
| Percentage of BusinessCombinationAcquisitionRelatedCosts | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 202 |
| Percentage of BusinessCombinationConsiderationTransferred1 | 100.0 |
| Period End | 2021-04-23 |
| Value | 96 |
| Percentage of BusinessCombinationConsiderationTransferred1 | 0.0 |
| Period End | 2021-01-12 |
| Value | 132 |
| Percentage of BusinessCombinationConsiderationTransferred1 | 0.0 |
| Period End | 2020-11-20 |
| Value | 55 |
| Percentage of BusinessCombinationConsiderationTransferred1 | 0.0 |
| Period End | 2020-11-20 |
| Value | 9.0 |
| Percentage of BusinessCombinationConsiderationTransferred1 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 38 | 37 | 32 | 22 | 22 | 22 | 22 | 19 | 18 | 17 | 17 |
| Percentage of CapitalizedContractCostAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 5.0 | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 | 3.0 | 1.0 | 2.0 | 1.0 |
| Percentage of CapitalizedContractCostAmortization | 13.2 | 16.2 | 18.8 | 27.3 | 27.3 | 27.3 | 27.3 | 15.8 | 5.6 | 11.8 | 5.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 32 | 30 | 25 | 15 | 15 | 16 | 15 | 15 | 16 | 15 | 15 |
| Percentage of CapitalizedContractCostAmortization | 84.2 | 81.1 | 78.1 | 68.2 | 68.2 | 72.7 | 68.2 | 78.9 | 88.9 | 88.2 | 88.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 | 1.0 | 1.0 | 0.0 | 1.0 |
| Percentage of CapitalizedContractCostAmortization | 2.6 | 2.7 | 3.1 | 4.5 | 4.5 | 0.0 | 4.5 | 5.3 | 5.6 | 0.0 | 5.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -8000000.0 | -9000000.0 | -9000000.0 | 0 | -9000000.0 | -10000000.0 | -9000000.0 | -7000000.0 | -1000000.0 | -8000000.0 |
| Percentage of CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-08-03 | 2020-07-30 | 2020-04-30 | 2020-02-18 | 2019-08-01 |
| Value | 0.3125 | 0.3125 | 0.21 | 0.21 | 0.2 |
| Percentage of CommonStockDividendsPerShareDeclared | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 |
| Value | 3000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 0 | 0 | 0 | 0 |
| Percentage of CostsIncurredDevelopmentCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 2000000.0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1000000.0 |
| Percentage of CostsIncurredDevelopmentCosts | 66.7 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 1000000.0 | 2000000.0 | 1000000.0 | 2000000.0 | 0 |
| Percentage of CostsIncurredDevelopmentCosts | 33.3 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 |
| Value | 131 | 128 | 128 | 125 | 102 | 99 | 102 | 111 | 112 | 89 | 84 | 84 | 84 | 82 | 81 | 93 | 88 | 78 | 75 | 74 | 77 | 75 | 74 | 75 |
| Percentage of DepreciationAmortizationAndAccretionNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-06-30 | 2019-03-31 |
| Value | 36 | 28 | 22 | -4.0 | 0.0 | 3.0 | 5.0 | 0.0 | 7.0 |
| Percentage of DerivativeLossOnDerivative | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 1.0 | 0 | 1.0 | 0 | -1.0 | 1.0 | 1.0 | 2.0 |
| Percentage of DerivativeNonmonetaryNotionalAmountEnergyMeasure | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | -1.0 | 5.0 | 8.0 | 6.0 | 0 | 0 | 2.0 | 2.0 |
| Percentage of DerivativeNonmonetaryNotionalAmountEnergyMeasure | -100.0 | 0.0 | 800.0 | 0.0 | -0.0 | 0.0 | 200.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 63 | 42 | 42 | 39 | 38 | 39 | 58 | 55 |
| Percentage of DividendsCommonStock | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 67 | 66 | 66 | 63 | 42 | 42 |
| Percentage of DividendsCommonStock | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 39 | 38 | 38 | 36 | 24 | 24 |
| Percentage of DividendsCommonStock | 0.0 | 0.0 | 0.0 | 57.1 | 57.1 | 57.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 28 | 28 | 28 | 27 | 18 | 18 |
| Percentage of DividendsCommonStock | 0.0 | 0.0 | 0.0 | 42.9 | 42.9 | 42.9 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 36 | 24 | 24 | 22 | 21 | 22 | 32 | 29 |
| Percentage of DividendsCommonStock | 57.1 | 57.1 | 57.1 | 56.4 | 55.3 | 56.4 | 55.2 | 52.7 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 27 | 18 | 18 | 17 | 17 | 17 | 26 | 26 |
| Percentage of DividendsCommonStock | 42.9 | 42.9 | 42.9 | 43.6 | 44.7 | 43.6 | 44.8 | 47.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2014-03-31 | 2013-03-31 |
| Value | 9.0 | 3.0 | 13 | 10.0 | 41 | 5.0 | 5.0 | 2.0 | 10.0 | 11 | 11 | 12 | 26 | 19 | 13 | 20 | 23 | 16 | 13 | 10.0 | 17 | 15 | 7.0 | 3.0 | 8.0 | 3.0 | -6.0 |
| Percentage of EquityMethodInvestmentDividendsOrDistributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 8000000.0 |
| Percentage of EquityMethodInvestmentOtherThanTemporaryImpairment | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-06-30 |
| Value | 0.0 | 0.0 | 49 | 0.0 |
| Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal | 0.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 0.0 | 0.0 | 49 |
| Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal | 0.0 | 0.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -37000000.0 | -33000000.0 | -24000000.0 | 0 | -3000000.0 | -5000000.0 | -1000000.0 | -2000000.0 | 0 | 0 | 0 | 0 |
| Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 |
| Value | 0 | -9000000.0 | 0 | 0 | 13000000.0 | 0 | 0 | 7000000.0 | 0 | 0 | 0 |
| Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 |
| Value | 3000000.0 | 2000000.0 |
| Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 1022 |
| Percentage of FinitelivedIntangibleAssetsAcquired1 | 100.0 |
| Period End | 2021-04-23 |
| Value | 2.0 |
| Percentage of FinitelivedIntangibleAssetsAcquired1 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 |
| Value | -7000000.0 | 4000000.0 | 0 | 0 | -4000000.0 | 2000000.0 | -5000000.0 | -2000000.0 | -2000000.0 | 1000000.0 | 3000000.0 | -2000000.0 | -8000000.0 | -4000000.0 | -1000000.0 | -3000000.0 | -1000000.0 | -1000000.0 | -4000000.0 | 0 | -1000000.0 | 0 |
| Percentage of GainLossOnSaleOfPropertyPlantEquipment | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 | 2012-09-30 | 2012-06-30 |
| Value | 20 | 8.0 | 4.0 | -15.0 | 19 | 16 | -13.0 | 31 | 38 | 11 | 3.0 | 9.0 | 32 | 29 | 4.0 | 8.0 | 28 | 16 | 19 | 8.0 | 13 | 18 | 2.0 | 6.0 | 19 | 9.0 | 1.0 | 1.0 | 11 | 14 | 1.0 | 4.0 | 12 | 2.0 | 4.0 | 4.0 | 6.0 | 6.0 |
| Percentage of IncomeLossFromEquityMethodInvestments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 2.0 | 2.0 | 2.0 | 2.0 | 3.0 | 1.0 | 2.0 | 2.0 | 3.0 | 2.0 | 2.0 | 3.0 | 3.0 |
| Percentage of IncomeLossFromEquityMethodInvestments | 10.0 | 25.0 | 50.0 | -13.3 | 15.8 | 6.2 | -15.4 | 6.5 | 7.9 | 18.2 | 66.7 | 33.3 | 9.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 18 | 6.0 | 2.0 | -17.0 | 16 | 15 | -15.0 | 29 | 35 | 9.0 | 1.0 | 6.0 | 29 |
| Percentage of IncomeLossFromEquityMethodInvestments | 90.0 | 75.0 | 50.0 | 113.3 | 84.2 | 93.8 | 115.4 | 93.5 | 92.1 | 81.8 | 33.3 | 66.7 | 90.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | -30.0 | -47.0 | 27 | 19 | 37 | -15.0 | -85.0 | 16 | -31.0 | -42.0 | -28.0 | -23.0 | 7.0 | 9.0 | 23 | 14 | 6.0 | -7.0 | 3.0 | 14 | 3.0 | 4.0 | -2.0 | 9.0 | 1.0 | 33 | 2.0 | -14.0 | 5.0 | 0.0 | 0.0 | 7.0 | 4.0 | 8.0 | 2.0 | 1.0 |
| Percentage of IncreaseDecreaseInDerivativeAssetsAndLiabilities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2012-12-31 |
| Value | 1.0 | 7.0 | -20.0 | -5.0 | 9.0 | 26 | -22.0 | 6.0 | -11.0 | 4.0 | -7.0 | 45 | 11 | 7.0 | -1.0 | 57 | 8.0 | 8.0 | -1.0 | -26.0 | 13 | 12 | 0.0 | 4.0 | 8.0 | 4.0 | -4.0 | -11.0 | 10.0 | 2.0 | 3.0 | 3.0 | 0.0 |
| Percentage of IncreaseDecreaseInIncomeTaxes | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 7.0 | 7.0 | 8.0 | 6.0 | 5.0 | 5.0 | 5.0 | 6.0 |
| Percentage of LeaseCost | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0 | -0.03 | 41.994 | -0.0028 | 0.4287 |
| Percentage of LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 |
| Value | 0 |
| Percentage of LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0.03 | 57.006 | 0.0028 | 0.5713 |
| Percentage of LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest | -100.0 | 135.7 | -100.0 | 133.3 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -1.0 | 118 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -1.0 | 118 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | -1.0 | 43 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 4.0 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 0.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | -1.0 | 43 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 4.0 |
| Percentage of MinorityInterestDecreaseFromRedemptions | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 | 2019-03-31 |
| Value | 1.0 | 103 | 2.0 | 4.0 | 12 |
| Percentage of NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-03-31 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 38 | 126 | 150 | 19 | 79 | 30 |
| Percentage of NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest | 3800.0 | 122.3 | 3750.0 | 158.3 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 | 2019-03-31 |
| Value | 1.0 | 103 | 2.0 | 4.0 | 12 |
| Percentage of NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-03-31 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 38 | 126 | 150 | 19 | 79 | 30 |
| Percentage of NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest | 3800.0 | 122.3 | 3750.0 | 158.3 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 5.0 | 5.0 | 5.0 | 4.0 | 7.0 | 2.0 | 2.0 | 2.0 |
| Percentage of OperatingLeaseCost | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 254 | 275 | 294 | 225 | 252 | 244 | 179 | 246 |
| Percentage of OperatingLeaseLeaseIncome | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 322 | 343 | 254 | 275 | 294 | 225 | 252 | 244 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 120 | 113 | 107 | 119 | 112 | 107 | 89 | 85 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 42.1 | 43.3 | 38.1 | 47.6 | 35.3 | 34.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 202 | 230 | 147 | 156 | 182 | 118 | 163 | 159 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 57.9 | 56.7 | 61.9 | 52.4 | 64.7 | 65.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 120 | 113 | 107 | 119 | 112 | 107 | 89 | 85 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 42.1 | 43.3 | 38.1 | 47.6 | 35.3 | 34.8 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 3.0 | 2.0 | 1.0 | 3.0 | 1.0 | 2.0 | 2.0 | 1.0 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 0.4 | 1.1 | 0.3 | 0.9 | 0.8 | 0.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 198 | 228 | 145 | 153 | 181 | 115 | 160 | 157 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 57.1 | 55.6 | 61.6 | 51.1 | 63.5 | 64.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 1.0 | 0.0 | 1.0 | 0.0 | 0.0 | 1.0 | 1.0 | 1.0 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 0.4 | 0.0 | 0.0 | 0.4 | 0.4 | 0.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 123 | 115 | 108 | 122 | 113 | 109 | 91 | 86 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 42.5 | 44.4 | 38.4 | 48.4 | 36.1 | 35.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 198 | 228 | 145 | 153 | 181 | 115 | 160 | 157 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 57.1 | 55.6 | 61.6 | 51.1 | 63.5 | 64.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 |
| Value | 1.0 | 0.0 | 1.0 | 0.0 | 0.0 | 1.0 | 1.0 | 1.0 |
| Percentage of OperatingLeaseLeaseIncome | 0.0 | 0.0 | 0.4 | 0.0 | 0.0 | 0.4 | 0.4 | 0.4 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 107 | 119 | 112 | 107 | 89 | 85 | 79 | 86 |
| Percentage of OperatingLeaseLeaseIncome | 42.1 | 43.3 | 38.1 | 47.6 | 35.3 | 34.8 | 44.1 | 35.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 147 | 156 | 182 | 118 | 163 | 159 | 100 | 160 |
| Percentage of OperatingLeaseLeaseIncome | 57.9 | 56.7 | 61.9 | 52.4 | 64.7 | 65.2 | 55.9 | 65.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 108 | 122 | 113 | 109 | 91 | 86 | 80 | 88 |
| Percentage of OperatingLeaseLeaseIncome | 42.5 | 44.4 | 38.4 | 48.4 | 36.1 | 35.2 | 44.7 | 35.8 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 145 | 153 | 181 | 115 | 160 | 157 | 99 | 158 |
| Percentage of OperatingLeaseLeaseIncome | 57.1 | 55.6 | 61.6 | 51.1 | 63.5 | 64.3 | 55.3 | 64.2 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 |
| Value | 1.0 | 0.0 | 0.0 | 1.0 | 1.0 | 1.0 | 0.0 | -0.0 |
| Percentage of OperatingLeaseLeaseIncome | 0.4 | 0.0 | 0.0 | 0.4 | 0.4 | 0.4 | 0.0 | -0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 |
| Value | 6.0 | 3.0 | 3.0 | 7.0 | -3.0 | 0.0 |
| Percentage of OperatingLeasePayments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -2000000.0 | 0 | 2000000.0 | -1000000.0 | 1000000.0 | -2000000.0 | 1000000.0 | 0 | 0 | 0 |
| Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 117 | 107 | 110 | 95 | 87 | 93 |
| Percentage of OtherCostAndExpenseOperating | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-01-12 |
| Value | 5000000.0 |
| Percentage of PaymentsForFees | 100.0 |
| Period End | 2021-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 |
| Value | -4.0 | 0.0 | 0.0 | -4.0 | 0.0 | 1.0 | -3.0 | -3.0 | -1.0 | -3.0 | -4.0 | -7.0 | 0.0 | 0.0 | 0.0 | 0.0 | -2.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | -11.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of PaymentsForProceedsFromOtherInvestingActivities | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2019-12-31 | 2019-09-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 | 2012-12-31 |
| Value | 0.0 | -2.0 | 15 | 10.0 | 8.0 | 10.0 | 0.0 | 9.0 | 0.0 | 5.0 | 0.0 | 0.0 | 0.0 | 1.0 | 3.0 | 1.0 | 6.0 | 0.0 | 0.0 | 0.0 | 2.0 | 11 | 0.0 | 1.0 | 13 | 5.0 | 8.0 | 0.0 | 1.0 | 0.0 | 4.0 | 1.0 |
| Percentage of PaymentsOfDebtIssuanceCosts | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 67 | 66 | 66 | 64 | 63 | 42 | 42 | 39 | 39 | 38 | 39 |
| Percentage of PaymentsOfOrdinaryDividends | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-11-20 |
| Value | 64 |
| Percentage of PaymentsToAcquireBusinessesGross | 100.0 |
| Period End | 2020-12-21 |
| Value | 23 |
| Percentage of PaymentsToAcquireBusinessesGross | 0.0 |
| Period End | 2021-01-31 |
| Value | 1.0 |
| Percentage of PaymentsToAcquireBusinessesGross | 0.0 |
| Period End | 2020-11-02 |
| Value | 24 |
| Percentage of PaymentsToAcquireBusinessesGross | 0.0 |
| Period End | 2020-11-02 |
| Value | 20 |
| Percentage of PaymentsToAcquireBusinessesGross | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2014-09-30 | 2013-09-30 |
| Value | 0.0 | 1.0 | 3.0 | 7.0 | -1.0 | 5.0 | 5.0 | 4.0 | 18 | 2.0 | 0.0 |
| Percentage of PaymentsToAcquireEquityMethodInvestments | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 |
| Period End | 2020-09-01 |
| Value | 79 |
| Percentage of PaymentsToAcquireEquityMethodInvestments | 0.0 |
| Period End | 2020-09-30 | 2019-06-30 | 2019-03-31 | 2018-06-30 | 2018-03-31 |
| Value | 0.0 | 0.0 | 19 | 0.0 | 0.0 |
| Percentage of PaymentsToAcquireInterestInSubsidiariesAndAffiliates | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2020-11-02 |
| Value | 44 |
| Percentage of PaymentsToAcquireInterestInSubsidiariesAndAffiliates | 0.0 |
| Period End | 2020-09-30 |
| Value | 0.0 |
| Percentage of PaymentsToMinorityShareholders | 0.0 |
| Period End | 2021-09-30 |
| Value | 0 |
| Percentage of ProceedsFromCollectionOfNotesReceivable | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 |
| Value | 17 | 12 | 8.0 | 26 | 30 | 11 | 12 | 19 | 20 | 3.0 | 14 | 23 | 4.0 | 4.0 | 14 | 15 | 7.0 | 9.0 | 16 | 12 | -13.0 | 21 | 8.0 | 26 | 1.0 |
| Percentage of ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 2000000.0 | 0 | 3000000.0 | 2000000.0 | 0 | 0 |
| Percentage of ProceedsFromInsuranceSettlementInvestingActivities | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2014-12-31 | 2014-09-30 | 2013-12-31 | 2013-07-22 | 2012-12-31 |
| Value | 4.0 | 20 | 28 | 10.0 | 100 | 0.0 | 0.0 | 0.0 | 2.0 | 76 | 65 | 10.0 | 0.0 | 18 | 9.0 | 7.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | -1.0 | 0.0 | 630 | 0.0 | 468 | 0.0 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-02 | 2018-09-27 |
| Value | 4.0 | 100 | 75 |
| Percentage of ProceedsFromIssuanceOrSaleOfEquity | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 1.0 |
| Percentage of ProceedsFromIssuanceOrSaleOfEquity | 25.0 |
| Period End | 2020-12-31 |
| Value | 3.0 |
| Percentage of ProceedsFromIssuanceOrSaleOfEquity | 75.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 |
| Value | 77 | 105 | 195 | 0.0 | 0.0 | 85 | 180 | 130 | 0.0 | 22 | 0.0 | 0.0 | 0.0 | 15 | 20 | 55 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 10.0 | 50 |
| Percentage of ProceedsFromLinesOfCredit | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2020-11-02 |
| Value | 30 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-11-02 |
| Value | 467 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-09-30 |
| Value | 16 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-09-30 |
| Value | 193 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-09-01 |
| Value | 16 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-09-01 |
| Value | 296 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-11-02 |
| Value | 30 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2020-11-02 |
| Value | 467 |
| Percentage of ProceedsFromLinesOfCredit | 0.0 |
| Period End | 2021-09-30 | 2020-12-31 | 2020-09-30 |
| Value | 77 | 0.0 | 0.0 |
| Percentage of ProceedsFromLinesOfCredit | 100.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-01-12 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-03-31 | 2018-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 |
| Value | -14.0 | 210 | 100 | -7.0 | 0.0 | 154 | 19 | 30 | -2.0 | -1.0 | -2.0 | 10.0 | 3.0 | 0.0 | 119 | 0.0 | 190 | 0.0 |
| Percentage of ProceedsFromMinorityShareholders | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2021-01-12 |
| Value | 210 |
| Percentage of ProceedsFromMinorityShareholders | 100.0 |
| Period End | 2021-01-12 |
| Value | 103 |
| Percentage of ProceedsFromMinorityShareholders | 49.0 |
| Period End | 2021-01-12 |
| Value | 107 |
| Percentage of ProceedsFromMinorityShareholders | 51.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | -1.0 | -4.0 | 13 |
| Percentage of ProceedsFromPaymentsForOtherFinancingActivities | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 |
| Value | 229 | -7.0 | 0.0 | 154 | -4.0 | -1.0 | 64 | 30 | 0.0 | -2.0 | 1.0 | 14 | -2.0 | -1.0 | -2.0 | 10.0 |
| Percentage of ProceedsFromPaymentsToMinorityShareholders | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-06-30 | 2019-03-31 |
| Value | 0.0 | 0.0 | 75 | 15 | 0.0 | 0.0 |
| Percentage of ProceedsFromSaleOfProductiveAssets | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-06-30 |
| Value | -3.0 | -2.0 | -2.0 | 13 | -2.0 | -1.0 | -2.0 | 31 | 2.0 | 14 | -3.0 | 2.0 |
| Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 3.0 | 4.0 | 3.0 | 3.0 | 2.0 | 2.0 | 2.0 | 1.0 | 2.0 |
| Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2017-12-31 | 2017-09-30 |
| Value | 13 | 14 | 13 | 10.0 | 9.0 | 9.0 | 9.0 | 9.0 | 8.0 | 9.0 | 7.0 | 8.0 | 7.0 | 8.0 | 6.0 | 5.0 |
| Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | 433.3 | 350.0 | 433.3 | 0.0 | 300.0 | 450.0 | 450.0 | 0.0 | 400.0 | 900.0 | 350.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 117 |
| Percentage of RepaymentsOfDebt | 100.0 |
| Period End | 2020-09-30 |
| Value | 14 |
| Percentage of RepaymentsOfDebt | 12.0 |
| Period End | 2020-09-30 |
| Value | 27 |
| Percentage of RepaymentsOfDebt | 23.1 |
| Period End | 2020-09-01 |
| Value | 247 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 107 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 92 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 73 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2021-01-12 |
| Value | 176 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 102 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2021-03-10 |
| Value | 53 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 107 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2021-10-31 | 2021-07-31 |
| Value | 32 | 67 |
| Percentage of RepaymentsOfDebt | 0.0 | 0.0 |
| Period End | 2020-11-02 |
| Value | 92 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 73 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2020-11-02 |
| Value | 102 |
| Percentage of RepaymentsOfDebt | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2019-12-31 | 2019-09-30 | 2018-12-31 | 2018-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 |
| Value | 67 | 63 | 170 | 0.0 | 0.0 | 130 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 318 | 8.0 | 40 |
| Percentage of RepaymentsOfLinesOfCredit | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2020-12-31 | 2020-09-30 |
| Value | 67 | 0.0 | 0.0 |
| Percentage of RepaymentsOfLinesOfCredit | 100.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 |
| Value | 1.0 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 100.0 |
| Period End | 2021-03-31 |
| Value | 273 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 0.0 |
| Period End | 2021-03-31 |
| Value | 273 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 0.0 |
| Period End | 2021-06-30 |
| Value | 1.0 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 100.0 |
| Period End | 2021-02-03 |
| Value | 51.0 |
| Percentage of SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest | 100.0 |
| Period End | 2021-02-03 |
| Value | 51.0 |
| Percentage of SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest | 100.0 |
| Period End | 2021-09-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2013-07-22 |
| Value | 3.0 | 11 | 8.0 | 4.0 | -12.0 | -1.0 | 5.0 | -2.0 | 6.0 | 7.0 | 17 | 19 |
| Percentage of UnrealizedGainLossOnDerivatives | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 | 2014-06-30 | 2014-03-31 |
| Value | 6.0 | -11.0 | 47 | 15 | 39 | -13.0 | -79.0 | 17 | -28.0 | -36.0 | -18.0 | -25.0 | 9.0 | 7.0 | 24 | 5.0 | -7.0 | 11 | 2.0 | -5.0 | -2.0 | 2.0 | 7.0 | 3.0 | -6.0 | 31 | 12 | -16.0 | 0.0 | -3.0 | 3.0 |
| Percentage of UnrealizedGainLossOnDerivatives | 200.0 | 0.0 | 427.3 | 0.0 | 487.5 | -325.0 | 658.3 | 0.0 | 2800.0 | -720.0 | 900.0 | 0.0 | 150.0 | 100.0 | 141.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-03-31 |
| Value | -37.0 | -33.0 | -24.0 | -7.0 | 16 | -3.0 | -5.0 | 0.0 |
| Percentage of UnrealizedGainLossOnDerivatives | -1233.3 | 0.0 | -218.2 | 0.0 | 200.0 | -75.0 | 41.7 | -0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 1.0 | 1.0 | 4.0 | 4.0 | 2.0 | -6.0 | -1.0 | 3.0 | -1.0 | 3.0 | 3.0 | 8.0 |
| Percentage of UnrealizedGainLossOnDerivatives | 33.3 | 0.0 | 36.4 | 50.0 | 50.0 | 50.0 | 100.0 | 60.0 | 50.0 | 50.0 | 42.9 | 47.1 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 |
| Value | 2.0 | -1.0 | 7.0 | 4.0 | 2.0 | -6.0 | 0.0 | 2.0 | -1.0 | 3.0 | 4.0 | 9.0 |
| Percentage of UnrealizedGainLossOnDerivatives | 66.7 | 0.0 | 63.6 | 50.0 | 50.0 | 50.0 | -0.0 | 40.0 | 50.0 | 50.0 | 57.1 | 52.9 |
| Period End | 2021-02-03 |
| Value | 51.0 |
| Percentage of VariableInterestEntityOwnershipPercentage | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | 2000000.0 | 2000000.0 | 3000000.0 | 2000000.0 | -2000000.0 | 3000000.0 | 3000000.0 | 4000000.0 |
| Percentage of VariableLeaseCost | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 126 | 129 |
| Percentage of ATMProgramAvailableForIssuance | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 |
| Value | 5.0 | 6.0 | 7.0 | 9.0 | 16 |
| Percentage of AccumulatedOtherComprehensiveIncomeLossCumulativeChangeInGainLossFromCashFlowHedgesTaxAmount | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-02-03 |
| Value | 35.0 |
| Percentage of AssetAcquisitionPercentageEquityInterestsAcquired | 100.0 |
| Period End | 2020-11-20 |
| Value | 17 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedLiabilitiesOther | 100.0 |
| Period End | 2020-12-21 |
| Value | 11 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedLiabilitiesOther | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 106 | 223 | 68 | 212 |
| Percentage of CapitalExpenditures | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 12 | 4.0 | 14 |
| Percentage of CapitalExpenditures | 11.3 | 1.8 | 20.6 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 44 | 185 | 26 |
| Percentage of CapitalExpenditures | 41.5 | 83.0 | 38.2 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 50 | 34 | 28 |
| Percentage of CapitalExpenditures | 47.2 | 15.2 | 41.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-03-31 | 2019-09-30 | 2019-03-31 | 2018-09-30 |
| Value | 3000000.0 | 3000000.0 | 3000000.0 | 4000000.0 | 4000000.0 | -3000000.0 | 3000000.0 | -3000000.0 | 3000000.0 |
| Percentage of CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonthsTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-17 |
| Value | 183 |
| Percentage of DebtInstrumentRepurchasedFaceAmountOptionallyExercisedRemainingPrincipalNotValidlyTenderedAndPurchasedInTenderOffer | 100.0 |
| Period End | 2021-10-24 |
| Value | 227 |
| Percentage of DebtInstrumentRepurchasedFaceAmountOptionallyExercisedRemainingPrincipalNotValidlyTenderedAndPurchasedInTenderOffer | 0.0 |
| Period End | 2021-03-11 |
| Value | 6000000.0 |
| Percentage of DebtInstrumentRepurchasedFaceAmountSubjectToGuaranteedDeliveryProcedures | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 11 | 50 | 28 |
| Percentage of DeferredTaxAssetsInterestExpenseDisallowedCarryforwardinvestmentsinProjects | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 104 | 92 | 57 | 128 |
| Percentage of DeferredTaxAssetsNetExcludingValuationAllowance | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 |
| Value | -209.0 | -185.0 | -136.0 | -172.0 | -186.0 | -233.0 | -189.0 | -92.0 | -109.0 | -79.0 | -41.0 | -10.0 | 21 | -47.0 |
| Percentage of DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2017-12-31 |
| Value | -136.0 | -103.0 | -66.0 | -44.0 | -17.0 | -17.0 | -15.0 | -10.0 | -8.0 | -8.0 | -7.0 | -1.0 | 0.0 |
| Percentage of DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral | 65.1 | 55.7 | 48.5 | 25.6 | 9.1 | 7.3 | 7.9 | 10.9 | 7.3 | 10.1 | 17.1 | -4.8 | -0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 |
| Value | -73.0 | -82.0 | -70.0 | -128.0 | -169.0 | -216.0 | -174.0 | -82.0 | -101.0 | -71.0 | -34.0 | -10.0 | 22 | -47.0 |
| Percentage of DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral | 34.9 | 44.3 | 51.5 | 74.4 | 90.9 | 92.7 | 92.1 | 89.1 | 92.7 | 89.9 | 82.9 | 100.0 | 104.8 | 100.0 |
| Period End | 2020-10-31 |
| Value | 34 |
| Percentage of DistributionReserveAccountsDistributionsPaid | 100.0 |
| Period End | 2021-02-03 |
| Value | 35.0 |
| Percentage of EquityMethodInvestmentAdditionalOwnershipAcquired | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 |
| Value | 10000000.0 | 9000000.0 | 4000000.0 | 10000000.0 | 6000000.0 |
| Percentage of FairValueAssetsMeasuredOnRecurringBasisValuationTechniquesImpactOfCreditReserveToFairValue | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 |
| Value | -209.0 | -185.0 | -136.0 | -172.0 | -186.0 | -233.0 | -189.0 | -92.0 | -79.0 | -41.0 | -10.0 | 21 | -47.0 |
| Percentage of FairValueofGrossDerivativeAssetsLiabilitiesNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2017-12-31 |
| Value | -136.0 | -103.0 | -66.0 | -44.0 | -17.0 | -18.0 | -15.0 | -9.0 | -8.0 | -7.0 | -1.0 | 0.0 |
| Percentage of FairValueofGrossDerivativeAssetsLiabilitiesNet | 65.1 | 55.7 | 48.5 | 25.6 | 9.1 | 7.7 | 7.9 | 9.8 | 10.1 | 17.1 | -4.8 | -0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 |
| Value | -73.0 | -82.0 | -70.0 | -128.0 | -169.0 | -215.0 | -174.0 | -83.0 | -71.0 | -34.0 | -10.0 | 22 | -47.0 |
| Percentage of FairValueofGrossDerivativeAssetsLiabilitiesNet | 34.9 | 44.3 | 51.5 | 74.4 | 90.9 | 92.3 | 92.1 | 90.2 | 89.9 | 82.9 | 100.0 | 104.8 | 100.0 |
| Period End | 2020-12-31 | 2020-06-30 | 2020-03-31 |
| Value | 39.86 | 0.3986 | 0.3986 |
| Percentage of IncomeAllocationPercentage | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-06-30 | 2020-03-31 |
| Value | 60.14 | 0.6014 | 0.6014 |
| Percentage of IncomeAllocationPercentage | 150.9 | 150.9 | 150.9 |
| Period End | 2020-12-31 |
| Value | 50.01 |
| Percentage of IncomeAllocationPercentage | 125.5 |
| Period End | 2020-12-21 |
| Value | 50.0 |
| Percentage of IncomeAllocationPercentage | 0.0 |
| Period End | 2021-03-31 |
| Value | 15.0 |
| Percentage of IncomeAllocationPercentage | 0.0 |
| Period End | 2020-09-30 |
| Value | 332 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour | 100.0 |
| Period End | 2020-11-02 |
| Value | 172.0 |
| Percentage of NumberOfSolarProjects | 100.0 |
| Period End | 2020-11-02 |
| Value | 172.0 |
| Percentage of NumberOfSolarProjects | 100.0 |
| Period End | 2020-12-31 |
| Value | 100.0 |
| Percentage of PercentOfOtherFinancialInstrumentLiabilitiesUsingLevel3FairValueInputs | 100.0 |
| Period End | 2020-12-31 |
| Value | 25.0 |
| Percentage of PercentOfOtherFinancialInstrumentLiabilitiesUsingLevel3FairValueInputs | 25.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 80.0 | 0.8 |
| Percentage of PercentageOfOwnership | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 |
| Value | 95.0 | 0.95 | 0.95 | 0.95 |
| Percentage of PercentageofCashAvailableforDistributions | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 97.12 | 0.9712 | 0.9712 |
| Percentage of PercentageofCashAvailableforDistributions | 102.2 | 102.2 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 95.0 | 0.95 | 0.95 |
| Percentage of PercentageofCashAvailableforDistributions | 100.0 | 100.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 65.19 | 0.6519 | 0.6519 |
| Percentage of PercentageofCashAvailableforDistributions | 68.6 | 68.6 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 94.34 | 0.9434 | 0.9434 |
| Percentage of PercentageofCashAvailableforDistributions | 99.3 | 99.3 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 5.0 | 0.05 | 0.05 |
| Percentage of PercentageofCashAvailableforDistributions | 5.3 | 5.3 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 34.81 | 0.3481 | 0.3481 |
| Percentage of PercentageofCashAvailableforDistributions | 36.6 | 36.6 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 100.0 | 1.0 | 1.0 |
| Percentage of PercentageofCashAvailableforDistributions | 105.3 | 105.3 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 |
| Value | 5.0 | 0.05 | 0.05 | 0.05 |
| Percentage of PercentageofCashAvailableforDistributions | 5.3 | 5.3 | 5.3 | 5.3 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2018-09-30 |
| Value | 50.0 | 0.5 | 0.5 | 0.5 |
| Percentage of PercentageofCashAvailableforDistributions | 52.6 | 52.6 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 |
| Value | 64.0 | 54.0 | 46.0 | 9.0 |
| Percentage of PercentofDerivativeLiabilitiesUsingLevel3FairValueInputs | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 82.4 | 0.824 |
| Percentage of Percentoffacevalue | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | 4700.0 | 4700.0 | 4200.0 | 4200.0 | 6201.0 | 5991.0 | 5875.0 | 5875.0 | 5272.0 | 5272.0 | 5272.0 | 5272.0 |
| Percentage of PowerGenerationCapacityMegawatts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2018-12-31 | 2018-09-30 |
| Value | 39.0 | 36.0 | 36.0 | 139.0 | 133.0 | 133.0 |
| Percentage of PowerGenerationCapacityMegawatts | 0.6 | 0.6 | 0.6 | 2.4 | 2.5 | 2.5 |
| Period End | 2020-11-20 |
| Value | 160.0 |
| Percentage of PowerGenerationCapacityMegawatts | 0.0 |
| Period End | 2020-12-21 |
| Value | 192.0 |
| Percentage of PowerGenerationCapacityMegawatts | 0.0 |
| Period End | 2020-12-31 | 2020-11-02 | 2020-09-30 | 2020-06-30 |
| Value | 113.0 | 286.0 | 113.0 | 113.0 |
| Percentage of PowerGenerationCapacityMegawatts | 2.7 | 0.0 | 1.8 | 1.9 |
| Period End | 2020-11-02 |
| Value | 286.0 |
| Percentage of PowerGenerationCapacityMegawatts | 0.0 |
| Period End | 2020-09-01 |
| Value | 419.0 |
| Percentage of PowerGenerationCapacityMegawatts | 0.0 |
| Period End | 2021-09-30 |
| Value | 13 |
| Percentage of PowerPurchaseAgreementRefundableTaxCreditAggregateAmountUtilized | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | 14 | 10.0 | 6.0 | 24 |
| Percentage of PrepaidLongTermServiceAgreement | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-01-12 |
| Value | 176 |
| Percentage of RepaymentOfDebtAcquiredInAssetAcquisition | 100.0 |
| Period End | 2021-01-12 |
| Value | 176 |
| Percentage of RepaymentOfDebtAcquiredInAssetAcquisition | 100.0 |
| Period End | 2020-09-30 | 2020-03-31 | 2019-12-31 | 2018-12-31 | 2018-09-30 |
| Value | 1456.0 | 1530.0 | 1530.0 | 1385.0 | 1392.0 |
| Percentage of SteamAndChilledWaterCapacityMegawattsThermalEquivalent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 5.0 | 0.05 | 0.05 |
| Percentage of TaxableIncomeAllocationPostFlip | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 50.0 | 0.5 |
| Percentage of TaxableIncomeAllocationPostFlip | 1000.0 | 1000.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 99.0 | 0.99 | 0.99 |
| Percentage of TaxableIncomeAllocationPreFlip | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 |
| Value | 99.0 | 0.99 | 0.99 |
| Percentage of TaxableIncomeAllocationPreFlip | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 99.0 | 0.99 |
| Percentage of TaxableIncomeAllocationPreFlip | 100.0 | 100.0 |
| Period End | 2020-07-31 | 2020-04-30 | 2020-03-24 | 2020-01-31 | 2019-10-31 | 2019-07-31 | 2019-04-30 | 2019-01-31 | 2018-10-31 | 2018-07-31 | 2018-03-31 | 2018-01-31 | 2017-10-31 | 2017-07-31 | 2017-04-30 | 2017-01-31 | 2016-10-31 | 2016-07-31 | 2016-04-30 | 2016-01-31 | 2015-10-31 | 2015-07-31 | 2015-04-30 | 2015-01-31 | 2014-10-31 | 2014-07-31 | 2014-06-30 | 2014-04-30 | 2014-02-26 | 2013-10-31 | 2013-07-31 |
| Value | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 34 | 22 | 22 | 22 | 22 | 22 |
| Percentage of EntityCommonStockSharesOutstanding | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-07-31 | 2020-04-30 | 2020-03-24 | 2020-01-31 | 2019-10-31 | 2019-07-31 | 2019-04-30 | 2019-01-31 | 2018-10-31 | 2018-07-31 | 2018-03-31 | 2018-01-31 | 2017-10-31 | 2017-07-31 | 2017-04-30 | 2017-01-31 | 2016-10-31 | 2016-07-31 | 2016-04-30 | 2016-01-31 | 2015-10-31 | 2015-07-31 |
| Value | 80 | 79 | 79 | 78 | 73 | 73 | 73 | 73 | 73 | 69 | 65 | 64 | 64 | 63 | 63 | 62 | 62 | 62 | 62 | 62 | 62 | 62 |
| Percentage of EntityCommonStockSharesOutstanding | 233.0 | 229.3 | 229.3 | 227.9 | 212.0 | 211.9 | 211.9 | 211.9 | 211.3 | 199.9 | 188.9 | 187.2 | 187.1 | 184.3 | 182.8 | 181.5 | 181.5 | 181.5 | 181.5 | 181.5 | 181.5 | 181.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 203 | 203 | 159 | 143 | 156 | 161 | 99 | 116 | 131 | 91 | 104 | 141 | 132 | 82 | 95 |
| Percentage of AccountsReceivableNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 60 | 66 | 66 | 57 | 37 | 39 | 29 | 34 | 37 | 33 | 35 | 35 | 29 | 26 | 28 |
| Percentage of AccountsReceivableNet | 29.6 | 32.5 | 41.5 | 39.9 | 23.7 | 24.2 | 29.3 | 29.3 | 28.2 | 36.3 | 33.7 | 24.8 | 22.0 | 31.7 | 29.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 143 | 137 | 93 | 86 | 119 | 122 | 70 | 82 | 94 | 58 | 69 | 106 | 103 | 56 | 67 |
| Percentage of AccountsReceivableNet | 70.4 | 67.5 | 58.5 | 60.1 | 76.3 | 75.8 | 70.7 | 70.7 | 71.8 | 63.7 | 66.3 | 75.2 | 78.0 | 68.3 | 70.5 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-09-30 | 2016-06-30 | 2015-09-30 | 2015-06-30 |
| Value | 3.0 | 4.0 | -4.0 | 6.0 | 7.0 | -8.0 | 6.0 | -6.0 | -7.0 | -5.0 | -6.0 | -6.0 | -16.0 | -15.0 | -15.0 | -29.0 | 28 | -19.0 | 10.0 |
| Percentage of AociIncludingPortionAttributableToNoncontrollingInterestTax | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 | 2012-12-31 |
| Value | 117 | 75 | 67 | 55 | 48 | 39 | 18 | 6.0 | 4.0 |
| Percentage of AssetRetirementObligation | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 1.0 |
| Percentage of AssetsFairValueDisclosure | 100.0 |
| Period End | 2020-12-31 |
| Value | 29 |
| Percentage of AssetsFairValueDisclosure | 2900.0 |
| Period End | 2020-12-31 |
| Value | 560 |
| Percentage of AssetsNet | 100.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 549 | 557 | 557 | 567 | 573 | 575 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 150 | 149 | 147 | 145 | 143 | 141 | 138 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 25.9 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 804 |
| Percentage of AssetsNet | 143.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-05-29 |
| Value | 631 | 642 | 645 | 112 | 107 | 104 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 12 | 14 |
| Percentage of AssetsNet | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 24 | 23 | 24 | 20 | 15 | 10.0 | 8.0 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 3.6 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 65 | 61 | 44 | 29 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 5.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 31 | 39 | 49 | 63 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 11.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 75 | 73 | 72 | 66 | 57 | 52 | 48 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 11.8 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 47 | 52 | 64 | 74 | 10.0 | 10.0 | 10.0 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 13.2 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | -10.0 | 2.0 | 40 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 102 | 108 | 118 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 36 | 34 | 34 | 30 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 5.4 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 51 | 46 | 51 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 108 | 108 | 119 | 120 | 141 | 147 |
| Percentage of AssetsNet | 0.0 | 0.0 | 0.0 | 21.4 | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 90.1 |
| Percentage of BusinessAcquisitionPercentageOfVotingInterestsAcquired | 100.0 |
| Period End | 2020-11-20 |
| Value | 119 |
| Percentage of BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue | 100.0 |
| Period End | 2020-12-21 |
| Value | 52 |
| Percentage of BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue | 0.0 |
| Period End | 2020-11-20 |
| Value | 157 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets | 100.0 |
| Period End | 2020-12-21 |
| Value | 296 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets | 0.0 |
| Period End | 2020-11-20 |
| Value | 4.0 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets | 100.0 |
| Period End | 2020-12-21 |
| Value | 49 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets | 0.0 |
| Period End | 2020-11-20 |
| Value | 15 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill | 100.0 |
| Period End | 2020-12-21 |
| Value | 1.0 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill | 0.0 |
| Period End | 2020-11-20 | 2013-12-31 |
| Value | 17 | 1986 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities | 100.0 | 100.0 |
| Period End | 2020-12-21 |
| Value | 216 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities | 0.0 |
| Period End | 2020-12-21 |
| Value | 205 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt | 100.0 |
| Period End | 2020-11-20 |
| Value | 138 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment | 100.0 |
| Period End | 2020-12-21 |
| Value | 246 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment | 0.0 |
| Period End | 2020-11-20 |
| Value | 21 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest | 100.0 |
| Period End | 2020-12-21 |
| Value | 28 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest | 0.0 |
| Period End | 2020-11-02 |
| Value | 205 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest | 0.0 |
| Period End | 2020-12-21 |
| Value | 63 |
| Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 7914 | 8026 | 8041 | 7043 | 6792 | 6808 | 6634 | 6858 |
| Percentage of DebtInstrumentCarryingAmount | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 850 | 600 |
| Percentage of DebtInstrumentCarryingAmount | 12.1 | 8.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 850 | 850 | 850 | 850 | 850 | 850 | 600 | 600 |
| Percentage of DebtInstrumentCarryingAmount | 10.7 | 10.6 | 10.6 | 12.1 | 12.5 | 12.5 | 9.0 | 8.7 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 |
| Value | 700 | 712 | 716 |
| Percentage of DebtInstrumentCarryingAmount | 8.8 | 8.9 | 8.9 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 25 | 27 |
| Percentage of DebtInstrumentCarryingAmount | 0.4 | 0.4 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 14 | 15 |
| Percentage of DebtInstrumentCarryingAmount | 0.2 | 0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 13 | 14 | 14 | 14 |
| Percentage of DebtInstrumentCarryingAmount | 0.2 | 0.2 | 0.2 | 0.2 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 772 | 772 | 800 | 800 | 816 | 816 | 844 | 844 |
| Percentage of DebtInstrumentCarryingAmount | 9.8 | 9.6 | 9.9 | 11.4 | 12.0 | 12.0 | 12.7 | 12.3 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 24 | 25 | 25 | 25 |
| Percentage of DebtInstrumentCarryingAmount | 0.3 | 0.3 | 0.3 | 0.4 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 55 | 57 | 57 | 57 |
| Percentage of DebtInstrumentCarryingAmount | 0.7 | 0.7 | 0.7 | 0.8 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 57 | 60 |
| Percentage of DebtInstrumentCarryingAmount | 0.8 | 0.9 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 123 | 125 | 126 | 126 | 127 | 128 | 129 | 129 |
| Percentage of DebtInstrumentCarryingAmount | 1.6 | 1.6 | 1.6 | 1.8 | 1.9 | 1.9 | 1.9 | 1.9 |
| Period End | 2020-09-30 | 2020-06-30 | 2019-12-31 |
| Value | 103 | 104 | 0.0 |
| Percentage of DebtInstrumentCarryingAmount | 1.5 | 1.5 | 0.0 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 169 | 169 | 169 | 176 | 176 | 176 | 176 | 182 |
| Percentage of DebtInstrumentCarryingAmount | 2.1 | 2.1 | 2.1 | 2.5 | 2.6 | 2.6 | 2.7 | 2.7 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 156 | 175 |
| Percentage of DebtInstrumentCarryingAmount | 2.2 | 2.6 |
| Period End | 2021-09-30 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 141 | 156 | 156 | 156 | 568 | 582 | 582 | 582 |
| Percentage of DebtInstrumentCarryingAmount | 1.8 | 1.9 | 1.9 | 2.2 | 8.4 | 8.5 | 8.8 | 8.5 |