| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:CommonStockValue us-gaap:StatementClassOfStock us-gaap:CommonClassA | █▇▃▂▁▁▁▁▁▁▁▁▁▁▁▁▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁ | 5.1 | 4.5 | 1.8 | 0.6 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.6 | 0.6 | 0.342 | 0.215 | 0.215 | 0.215 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | NA | NA | NA |
| us-gaap:CommonStockValue us-gaap:StatementClassOfStock us-gaap:CommonClassB | NA | NA | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | NA | NA | NA | |
| us-gaap:CommonStockSharesAuthorized us-gaap:Range,us-gaap:StatementClassOfStock,us-gaap:SubsequentEventType,us-gaap:TypeOfArrangement srt:Maximum,us-gaap:CommonClassA,us-gaap:SubsequentEvent,amch:EquityDistributionAgreement | 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:CommonStockSharesAuthorized us-gaap:StatementClassOfStock,us-gaap:SubsequentEventType,us-gaap:TypeOfArrangement us-gaap:CommonClassA,us-gaap:SubsequentEvent,amch:EquityDistributionAgreement | 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:CommonStockSharesAuthorized us-gaap:StatementClassOfStock,us-gaap:SubsequentEventType,us-gaap:TypeOfArrangement us-gaap:CommonClassA,us-gaap:SubsequentEvent,amch:EquityOfferingsAtMarket | 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:CommonStockSharesAuthorized us-gaap:StatementClassOfStock,us-gaap:TypeOfArrangement us-gaap:CommonClassA,amch:EquityDistributionAgreement | ▄ | 241.6 | 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:WeightedAverageNumberOfDilutedSharesOutstanding | █▇▂▁▁▁▁▁▂▁▂▁▁▁▁▂▂▁ | 480.731 | 400.111 | 152.307 | 107.695 | 104.319 | 104.245 | 103.85 | 103.85 | 135.528 | 103.783 | 135.45 | 123.126 | 128.105 | 128.046 | 129.265 | 131.077 | 131.166 | 121.401 | NA | 98.284 | 98.304 | 98.207 | NA | 98.073 | 98.037 | 97.919 | 97.865 | 0.097628 | 0.09762812 | 0.09739009 | 78.092 | 0.076 | 0.07600003 | 0.07600003 |
| us-gaap:WeightedAverageNumberOfSharesOutstandingBasic | █▇▂▁▁▁▁▁▁▁▁▁▁▁▁▂▂▁ | 480.731 | 400.111 | 152.307 | 107.695 | 104.319 | 104.245 | 103.85 | 103.85 | 103.845 | 103.783 | 103.514 | 123.126 | 128.039 | 128.046 | 129.265 | 131.077 | 131.166 | 121.358 | NA | 98.194 | 98.194 | 98.2 | NA | 97.978 | 97.978 | 97.919 | 97.506 | 0.097506 | 0.09750668 | 0.09739009 | 78.092 | 0.076 | 0.07600003 | 0.07600003 |
| us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:DebtInstrument amch:SeniorUnsecuredConvertibleNotesDue2024 | NA | 31.7 | NA | 34.0 | 31.7 | NA | NA | 31.7 | NA | 31.7 | NA | 5.9 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:EarningsPerShareBasic | ▇▇▅▅▅▁▇▇▇▇▇▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇ | -0.71 | -1.42 | -6.21 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.48 | -1.25 | 1.65 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.2899999999999999 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.31 | 0.08 | 0.32 | -0.05 | 3.58 | 0.44 | 0.81 | -0.13 |
| us-gaap:EarningsPerShareDiluted | ▇▇▅▅▅▁▇▇▇▇▇▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇ | -0.71 | -1.42 | -6.21 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.17 | -1.25 | 0.43 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.2899999999999999 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.3 | 0.08 | 0.32 | -0.05 | 3.58 | 0.44 | 0.81 | -0.13 |
| us-gaap:IncomeLossFromContinuingOperationsPerBasicShare | ▇▇▆▅▅▁▇▇▇▇▇▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇ | -7.1e-07 | -1.42e-06 | -4.589999999999997e-06 | -8.41e-06 | -5.38e-06 | -2.088e-05 | -1.299999999999999e-07 | -5.3e-07 | 4.8e-07 | -1.25e-06 | 1.39e-06 | -8.2e-07 | 1.7000000000000001e-07 | 1.4e-07 | -2.1400000000000003e-06 | -3.3e-07 | -1.35e-06 | 7e-08 | 2.9e-07 | 3.1e-07 | 2.4e-07 | 2.9e-07 | 4.2e-07 | 1.2e-07 | 4.5000000000000003e-07 | 6e-08 | 3.1e-07 | 8e-08 | 3.2e-07 | -5.0000000000000004e-08 | 3.62e-06 | 4.5000000000000003e-07 | 8.100000000000001e-07 | -2.0000000000000002e-07 |
| us-gaap:IncomeLossFromContinuingOperationsPerDilutedShare | ▇▇▆▅▅▁▇▇▇▇▇▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇ | -7.1e-07 | -1.42e-06 | -4.589999999999997e-06 | -8.41e-06 | -5.38e-06 | -2.088e-05 | -1.299999999999999e-07 | -5.3e-07 | 1.7000000000000001e-07 | -1.25e-06 | 8.9e-07 | -8.2e-07 | 1.7000000000000001e-07 | 1.4e-07 | -2.1400000000000003e-06 | -3.3e-07 | -1.35e-06 | 7e-08 | 2.9e-07 | 3.1e-07 | 2.4e-07 | 2.9e-07 | 4.2e-07 | 1.2e-07 | 4.5000000000000003e-07 | 6e-08 | 3e-07 | 8e-08 | 3.2e-07 | -5.0000000000000004e-08 | 3.62e-06 | 4.5000000000000003e-07 | 8.100000000000001e-07 | -2.0000000000000002e-07 |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| COGS Ratio us-gaap:ProductOrService us-gaap:Admission | ▃▂▂▁▁▅█▇█▇█▇███▇ | 233.0 | 69.5 | 80.3 | 62.9 | 0.9 | 568.0 | 877.0 | 797.3 | 895.5 | 731.5 | 862.3 | 751.4 | 896.3 | 875.0 | 897.1 | 753.5 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| COGS Ratio us-gaap:ProductOrService us-gaap:FoodAndBeverage | ▃▂▂▁▁▅▇▇█▆▇▆▇▇▇▆ | 161.5 | 50.1 | 44.8 | 29.1 | 0.4 | 288.1 | 438.3 | 420.0 | 492.5 | 368.8 | 435.1 | 384.8 | 445.8 | 405.8 | 415.3 | 361.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Cost Ratio us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName amch:DigitalCinemaImplementationPartnersLLC | NA | NA | NA | 1.1 | NA | NA | NA | 40.1 | 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 |
| 2021-06-30 | 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 |
|---|
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AllocatedShareBasedCompensationExpense | █▁ | 8.4 | 5.4 | NA | NA | 3.7 | 2.7 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 1.087 | 1.103 | 2.199 | 1.439 | 5.739 | 5.221 | -1.596 | 1.311 | 6.357 | 12.0 | 0.0 | 0.0 | 0.0 |
| us-gaap:ComprehensiveIncomeNetOfTax | ▆▆▅▅▆▁▇▇▇▇█▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇ | -323.1 | -617.9 | -855.3 | -894.2 | -505.2 | -2269.8 | 57.1 | -122.9 | 40.2 | -155.1 | 150.0 | -107.9 | -85.0 | 28.2 | -256.6 | -9.0 | -100.0 | 6.5 | 24.352 | 30.91 | 24.641 | 26.409 | 43.275 | 10.216 | 42.803 | -2.478 | 17.926 | 5.936 | 31.551 | -2.693 | 297.037 | 23.177 | 64.95 | -6.004 |
| us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest | █▁ | -0.4 | -0.5 | 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:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest | ▇▆▅▅▆▁█▇ | -323.5 | -618.4 | -855.4 | -894.2 | -505.2 | -2269.8 | 57.1 | -122.9 | 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:CostOfGoodsAndServicesSold us-gaap:ProductOrService us-gaap:Admission | ▂▁▁▁▁▅▇▇█▆▇▆█▇▇▆ | 98.9 | 22.0 | 24.2 | 26.6 | 0.2 | 271.7 | 434.5 | 416.8 | 482.5 | 365.3 | 433.5 | 378.8 | 471.4 | 426.5 | 440.1 | 364.8 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService us-gaap:FoodAndBeverage | ▃▂▃▁▁▆█▇█▇▇▇█▇▇▆ | 26.3 | 9.7 | 22.1 | 8.8 | 4.5 | 53.4 | 73.6 | 67.2 | 76.4 | 61.5 | 68.9 | 63.6 | 72.2 | 66.2 | 69.5 | 60.7 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:CostsAndExpenses | ▂▁▃▂▁█▄▃▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▁▂▁▁▁▁▁▂▁▂▁ | 741.3 | 576.1 | 1132.1 | 794.9 | 490.5 | 2927.6 | 1404.3 | 1296.0 | 1400.6 | 1234.1 | 1326.0 | 1243.3 | 1352.8 | 1273.7 | 1346.4 | 1183.0 | 1221.9 | 1228.0 | 893.617 | 714.247 | 708.358 | 706.766 | 708.565 | 653.301 | 726.906 | 621.071 | 651.533 | 605.39 | 658.176 | 605.219 | 679.201 | 638.137 | 684.816 | 558.26 |
| us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal us-gaap:DisposalGroupClassification,us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations,amch:ForumCinemasOu | NA | 0.3 | -1.6 | 2.8 | 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:GainsLossesOnExtinguishmentOfDebt us-gaap:IncomeStatementLocation us-gaap:OtherExpense | NA | NA | 93.6 | 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:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | ▆▆▅▅▆▁▇▇█▇█▇███▇▇▇███████████▇███▇ | -349.2 | -574.0 | -952.9 | -901.2 | -567.3 | -2108.1 | -46.9 | -55.0 | 54.8 | -124.5 | 171.0 | -89.3 | 19.6 | 22.4 | 14.1 | -60.3 | -286.1 | -0.8 | 12.385 | 50.521 | 40.352 | 46.381 | 64.932 | 21.258 | 67.273 | 10.068 | 41.589 | 12.086 | 51.504 | -7.942 | 8.368 | 37.302 | 66.188 | -12.137 |
| us-gaap:IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest | ▇▆▅▅▆▁██ | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | -4.842 | NA | NA | NA | -15.237 |
| us-gaap:IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest | ▁█ | -0.4 | -0.3 | 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:IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:Parent | █▁ | -343.6 | -566.9 | 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:IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:RetainedEarnings | █▁ | -343.6 | -566.9 | 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:IncomeTaxExpenseBenefit | ▄▄▄▄▄▅▄▄▄▄▄▅▄▄█▄▃▄▅▅▅▅▅▅▅▄▅▄▅▄▁▄▄▄ | -5.2 | -6.8 | -6.8 | 4.6 | -6.1 | 68.2 | -33.4 | -0.2 | 5.4 | 5.7 | 0.4 | 11.1 | -2.6 | 4.7 | 290.5 | -17.6 | -109.6 | -9.2 | 19.2 | 20.085 | 16.385 | 18.09 | 23.315 | 9.08 | 23.35 | 3.93 | 11.77 | 4.71 | 20.09 | -3.1 | -274.243 | 3.43 | 4.33 | 3.1 |
| us-gaap:IncomeTaxExpenseBenefit us-gaap:StatementScenario amch:AttributableEarningsBeforeInterestTaxesDepreciationAmortization | ▆▁█▄▄▃█▆▆ | 0.1 | -0.2 | 0.2 | 0.0 | 0.0 | -0.1 | 0.2 | 0.1 | 0.1 | 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:IncomeTaxesPaidNet | ▂█▄▄▇▄▂▄▁▄█▄▅▅▄▅▆▄▃▃▅▄▆▃▂▃▃▃▄▄▄▃ | -2.9 | 9.0 | 0.9 | 0.9 | 7.0 | 1.7 | -1.8 | 2.1 | -4.5 | 2.5 | 9.6 | 1.5 | 3.9 | 4.5 | 1.3 | 3.1 | 5.5 | 1.0 | 0.146 | 0.502 | 3.284 | 0.806 | 6.379 | 0.102 | -1.635 | 0.505 | -0.806 | 0.015 | 0.566 | 1.309 | 1.149 | -0.339 | NA | NA |
| us-gaap:InterestExpense | ▅█▄▄▄▄▄▄▄▄▄▄▄▄▃▃▃▃▂▁▁▁ | 98.9 | 162.8 | 88.6 | 94.3 | 91.2 | 82.8 | 85.7 | 85.1 | 86.4 | 83.6 | 93.4 | 84.0 | 82.4 | 82.5 | 70.6 | 71.4 | 69.9 | 61.9 | 40.737 | 26.7 | 27.0 | 27.1 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:InterestExpenseDebt | ▅█▄▄▄▄▄▄▄▄▄▃▃▃▃▃▃▃▂▁▁▁▁▁▁▁▁▁▁▁▂▂▂▂ | 88.1 | 151.5 | 77.3 | 82.8 | 79.6 | 71.3 | 74.1 | 73.2 | 74.2 | 71.3 | 74.1 | 64.3 | 62.2 | 61.7 | 59.9 | 60.8 | 59.6 | 51.1 | 36.297 | 24.679 | 24.888 | 24.867 | 23.379 | 22.682 | 24.717 | 26.079 | 26.528 | 26.897 | 27.989 | 29.658 | 32.259 | 32.221 | 32.31 | 33.173 |
| us-gaap:NetIncomeLoss | ▆▆▅▅▆▁▇▇█▇█▇██▇▇▇█████ | -343.6 | -566.9 | -945.8 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49.4 | -130.2 | 170.6 | -100.4 | 22.2 | 17.7 | -276.4 | -42.7 | -176.5 | 8.4 | 29.0 | 30.4 | 24.0 | 28.3 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest | NA | -0.3 | 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:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:Parent | NA | -566.9 | NA | -905.8 | -561.2 | -2176.3 | NA | -54.8 | 49.4 | -130.2 | 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:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings | NA | -566.9 | NA | -905.8 | -561.2 | -2176.3 | NA | -54.8 | 49.4 | -130.2 | NA | -100.4 | 22.2 | 17.7 | NA | -42.7 | -176.5 | 8.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:NetIncomeLossAttributableToNoncontrollingInterest | ▁█ | -0.4 | -0.3 | 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:OperatingExpenses | ▄▆▁▆▅▆▇▇▆▆█▇▇▆█▆▆▇█▇▆▆ | -4.0 | 2.3 | -11.8 | 1.8 | -1.5 | 2.1 | 4.7 | 5.3 | 2.3 | 2.5 | 7.8 | 6.6 | 5.7 | 3.7 | 8.1 | 3.7 | 3.5 | 5.3 | 7.117 | 5.8 | 3.8 | 3.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:OperatingIncomeLoss | ▇▆▄▅▆▁████████████████████████████ | -296.6 | -427.8 | -969.6 | -675.4 | -471.6 | -1986.1 | 43.4 | 20.8 | 105.5 | -33.7 | 87.3 | -21.9 | 89.7 | 109.9 | 70.4 | -4.3 | -19.6 | 55.4 | 32.479 | 65.524 | 55.604 | 59.251 | 75.292 | 35.539 | 94.173 | 32.053 | 60.622 | 28.514 | 68.397 | 17.539 | 33.776 | 57.847 | 77.849 | 19.542 |
| us-gaap:OtherNonoperatingIncomeExpense | ▅▄▇▁▄▃▄▄▅▃█▃▄▄▄▄▄▄▄▄▄ | 42.7 | 17.4 | 116.4 | -125.0 | 6.6 | -26.9 | -8.3 | 1.3 | 23.4 | -29.8 | 165.6 | -54.1 | -2.2 | -1.2 | -0.6 | 0.6 | -1.0 | 2.7 | 0.441 | -0.079 | 0.11 | NA | -1.411 | 0.0 | -9.273 | NA | -0.053 | 0.011 | NA | NA | NA | NA | NA | NA |
| us-gaap:ProfitLoss | ▆▆▅▅▆▁▇▇█▇█▇██▇▇▇█ | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49.4 | -130.2 | 170.6 | -100.4 | 22.2 | 17.7 | -276.4 | -42.7 | -176.5 | 8.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:ProfitLoss us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName amch:DigitalCinemaImplementationPartnersLLC | NA | NA | NA | -30.6 | NA | NA | NA | 22.3 | 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:RevenueFromContractWithCustomerExcludingAssessedTax | ▃▂▂▁▁▅█▇█▇█▇▇▇█▆▇▇▅▅▅▅▅▄▅▄▄▄▄▄▄▄▅▄ | 444.7 | 148.3 | 162.5 | 119.5 | 18.9 | 941.5 | 1447.7 | 1316.8 | 1506.1 | 1200.4 | 1413.3 | 1221.4 | 1383.6 | 1383.6 | 1416.8 | 1178.7 | 1202.3 | 1281.4 | 926.096 | 779.771 | 763.962 | 766.017 | 783.857 | 688.84 | 821.079 | 653.124 | 712.155 | 633.904 | 726.573 | 622.758 | 712.977 | 695.984 | 762.665 | 577.802 |
| us-gaap:Revenues | ▃▂▂▁▁▅█▇█▇█▇█▇█▆▇▇▅▅▅▅▅▄▅▄▄▄▄▄▄▄▅▄ | 444.7 | 148.3 | 162.5 | 119.5 | 18.9 | 941.5 | 1447.7 | 1316.8 | 1506.1 | 1200.4 | 1413.3 | 1221.4 | 1442.5 | 1383.6 | 1416.8 | 1178.7 | 1202.3 | 1283.4 | 926.096 | 779.771 | 763.962 | 766.017 | 783.857 | 688.84 | 821.079 | 653.124 | 712.155 | 633.904 | 726.573 | 622.758 | 712.977 | 695.984 | 762.665 | 577.802 |
| 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 |
|---|
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:Assets | ▆▆▅▆▆▆████▅▅▅▅▅▅▅▅▄▁▁▁▁▁▁▁▁▁▁▁▁ | 11329.1 | 10488.7 | 10276.4 | 10876.2 | 11271.6 | 11238.3 | 13675.8 | 13281.3 | 13514.9 | 13473.2 | 9495.8 | 9363.0 | 9531.8 | 9685.7 | 9805.9 | 9910.7 | 9811.7 | 9940.0 | 8641.841 | 4969.256 | 4948.541 | 4931.071 | 5110.085 | 4667.16 | 4739.325 | 4662.755 | 4763.732 | 4612.915 | 4709.696 | 4813.028 | 5046.724 | NA | NA | NA |
| us-gaap:Liabilities | █████▇▇▇▇▇▄▄▄▄▄▄▄▄▃▁▁▁▁▁▁▁▁▁▁▁▁ | 12733.8 | 12775.7 | 13134.6 | 13211.6 | 12847.0 | 12312.3 | 12461.6 | 12098.0 | 12189.8 | 12169.7 | 8097.8 | 8108.1 | 7561.5 | 7600.4 | 7692.7 | 7485.5 | 7334.2 | 7338.3 | 6631.107 | 3402.475 | 3394.615 | 3383.737 | 3570.018 | 3151.862 | 3216.909 | 3164.947 | 3249.574 | 3102.336 | 3183.798 | 3300.425 | 3537.785 | NA | NA | NA |
| us-gaap:LiabilitiesAndStockholdersEquity | ▆▆▅▆▆▆████▅▅▅▅▅▅▅▅▄▁▁▁▁▁▁▁▁▁▁▁▁ | 11329.1 | 10488.7 | 10276.4 | 10876.2 | 11271.6 | 11238.3 | 13675.8 | 13281.3 | 13514.9 | 13473.2 | 9495.8 | 9363.0 | 9531.8 | 9685.7 | 9805.9 | 9910.7 | 9811.7 | 9940.0 | 8641.841 | 4969.256 | 4948.541 | 4931.071 | 5110.085 | 4667.16 | 4739.325 | 4662.755 | 4763.732 | 4612.915 | 4709.696 | 4813.028 | 5046.724 | NA | NA | NA |
| us-gaap:StockholdersEquity | ▃▂▁▂▃▃▆▆▆▆▆▆▇▇▇███▇▇▇▇▇▇▇▇▇▇▇▇▇ | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214.2 | 1183.3 | 1325.1 | 1303.5 | 1397.6 | 1254.5 | 1969.9 | 2084.8 | 2112.4 | 2424.4 | 2476.7 | 2600.6 | 2009.654 | 1565.701 | 1552.846 | 1546.254 | 1538.703 | 1513.934 | 1521.052 | 1496.382 | 1512.732 | 1509.153 | 1524.429 | 1511.134 | 1507.47 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment | ▂▂▁▂▂▂▂▄▄▄▄▃▃▃▄▄▄▄▄▄▄▄▄▄▄▄▆█ | -17.6 | -17.9 | -21.4 | -16.4 | -16.6 | -17.2 | -17.3 | -1.6 | -1.7 | -1.7 | -1.8 | -7.4 | -7.5 | -7.2 | -6.6 | -4.1 | -4.1 | -3.5 | -3.569 | -3.276 | -3.281 | -3.285 | -3.289 | -4.597 | -3.493 | -3.499 | 5.564 | 19.573 | NA | NA | 20.967 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncome | ▄▄▅▃▃▁▄▂▃▄▄▅▅██▇▆▄▄▄▄▄▄▄▄▄▅▅ | 8.2 | -12.3 | 38.7 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26.0 | 33.5 | 140.5 | 125.6 | 105.8 | 72.1 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12.844 | 24.737 | NA | NA | 24.204 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustment | ▅▄▆▃▃▁▄▁▃▃▄▅▅██▇▆▄▄▄▄▄▄▄▄▄▄▄ | 25.8 | 5.6 | 60.1 | -35.6 | -47.0 | -102.4 | -8.8 | -95.1 | -26.9 | -17.7 | 7.2 | 33.3 | 39.0 | 145.6 | 129.9 | 107.5 | 73.1 | -4.0 | -1.78 | 2.867 | 2.707 | 2.03 | 2.101 | 1.608 | 1.01 | 1.705 | 0.627 | 0.306 | NA | NA | -0.351 | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AssetsCurrent | █▄▂▃▃▂▃▂▃▂▃▃▃▃▄▃▃▄▃▁▁▁▂▂▂▂▂▂▂▃▃ | 2012.3 | 1016.0 | 487.0 | 608.6 | 679.7 | 551.8 | 673.1 | 448.7 | 590.0 | 551.6 | 781.3 | 686.5 | 840.9 | 738.1 | 872.4 | 622.0 | 622.3 | 891.0 | 683.643 | 195.627 | 255.472 | 286.673 | 414.367 | 347.991 | 462.551 | 387.853 | 509.739 | 369.288 | 474.918 | 601.486 | 843.523 | NA | NA | NA |
| us-gaap:CashAndCashEquivalentsAtCarryingValue | █▄▂▂▃▂▂▁▂▂▂▂▂▂▂▂▁▂▂▁▁▁▂▁▂▁▂▁▂▂▃▁▁▁ | 1811.2 | 813.1 | 308.3 | 417.9 | 498.0 | 299.8 | 265.0 | 100.4 | 190.5 | 184.6 | 313.3 | 333.3 | 316.4 | 300.9 | 310.0 | 260.0 | 127.8 | 313.1 | 207.073 | 46.312 | 93.316 | 107.927 | 211.25 | 97.939 | 179.34 | 144.804 | 218.206 | 155.506 | 235.305 | 353.277 | 546.454 | 130.628 | 136.307 | 106.376 |
| us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents | █▄▂▂▃▂▂▁▁▁▂▂▂▂▂▂▁▂▁ | 1839.6 | 842.1 | 321.4 | 428.8 | 508.4 | 309.8 | 275.5 | 110.6 | 201.2 | 195.2 | 324.0 | 344.3 | 327.4 | 312.5 | 318.3 | 291.4 | 159.9 | 336.4 | 230.2 | NA | NA | NA | 211.2 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:ReceivablesNetCurrent | ▂▂▂▃▂▄▇▅▇▆█▄▅▅█▄▄▄▆▁▂▂▃▁▂▁▃▁▂▁▃ | 88.5 | 86.0 | 91.0 | 97.5 | 70.7 | 126.8 | 254.2 | 157.9 | 228.5 | 193.8 | 259.5 | 155.2 | 179.1 | 167.1 | 271.5 | 128.9 | 153.8 | 144.8 | 213.667 | 57.741 | 67.231 | 85.048 | 105.509 | 56.794 | 81.849 | 48.211 | 99.252 | 42.938 | 63.55 | 53.316 | 106.148 | NA | NA | NA |
| us-gaap:OtherAssetsCurrent | ▁▁▁▁▂▃▄▅▄▄▆▅▆▆▆▇▇▆█▂▂▂▂▁▂▁▁▁▁▁▁ | 84.2 | 87.9 | 74.6 | 82.3 | 100.6 | 115.2 | 143.4 | 180.2 | 160.3 | 162.6 | 197.8 | 187.0 | 203.9 | 204.1 | 202.6 | 226.3 | 223.7 | 211.7 | 262.903 | 91.574 | 94.925 | 93.698 | 97.608 | 84.4 | 93.291 | 86.767 | 84.343 | 80.735 | 82.658 | 83.066 | 80.824 | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NoncurrentAssets | ▅▅▅▆▆▆████▄▄▄▅▅▅▅▅▄▄▄▄▁ | 9316.8 | 9472.7 | 9789.4 | 10267.6 | 10591.9 | 10686.5 | 13002.7 | 12832.6 | 12924.9 | 12921.6 | 8714.5 | 8676.5 | 8690.9 | 8947.6 | 8933.5 | 9288.7 | 9189.4 | 9049.0 | 7958.198 | 7958.2 | 7958.2 | 7958.2 | 4695.718 | NA | NA | NA | 4253.993 | NA | NA | NA | 4203.201 | NA | NA | NA |
| us-gaap:AssetsNoncurrent us-gaap:EquityMethodInvestmentNonconsolidatedInvestee us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | NA | NA | 347.4 | NA | NA | NA | 843.3 | 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 | NA | NA | 4492.4 | NA | NA | NA | 4388.3 | 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 amch:FurnitureFixturesAndEquipment | NA | NA | 2343.7 | NA | NA | NA | 2216.8 | 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:BuildingAndBuildingImprovements | NA | NA | 222.3 | NA | NA | NA | 230.4 | 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:Land | NA | NA | 92.6 | NA | NA | NA | 106.3 | 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:LeaseholdImprovements | NA | NA | 1833.8 | NA | NA | NA | 1834.8 | 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:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment | █▅▁ | 2417.7 | 2330.0 | 2232.1 | NA | NA | NA | 1812.5 | 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:PropertyPlantAndEquipmentNet | NA | NA | 2260.3 | 2332.5 | 2417.5 | 2520.4 | 2649.2 | 2581.4 | 2613.9 | 2600.8 | 3039.6 | 3028.6 | 3028.1 | 3091.3 | 3116.5 | 3244.5 | 3254.0 | 3162.2 | 3035.859 | 1537.951 | 1447.997 | 1409.634 | 1401.928 | 1313.526 | 1278.216 | 1266.86 | 1247.23 | 1214.036 | 1207.608 | 1192.034 | 1179.754 | NA | NA | NA | |
| us-gaap:Goodwill | ▁▂▂▃▃▃█▇██████████▅▁▁▁▁▁▁▁▁▁▁▁▁ | 2472.1 | 2491.0 | 2547.3 | 2874.4 | 2988.4 | 2938.0 | 4789.1 | 4693.8 | 4763.0 | 4787.9 | 4788.7 | 4820.8 | 4830.7 | 4944.2 | 4931.7 | 4889.5 | 4832.2 | 4823.7 | 3932.96 | 2410.713 | 2410.713 | 2410.58 | 2406.691 | 2289.8 | 2289.8 | 2289.8 | 2289.8 | 2289.8 | 2289.8 | 2289.8 | 2289.8 | NA | NA | NA |
| us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill | NA | NA | 152.5 | NA | NA | NA | 165.6 | NA | NA | NA | 166.5 | NA | NA | NA | 169.4 | NA | NA | NA | 155.259 | NA | NA | NA | 112.6 | NA | NA | NA | 104.4 | NA | NA | NA | 104.4 | NA | NA | NA | |
| us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueInputsLevel3,us-gaap:FairValueMeasurementsNonrecurring | NA | NA | 44.0 | 43.8 | 50.3 | 50.3 | 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:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:FairValueByMeasurementBasis,us-gaap:FairValueByMeasurementFrequency us-gaap:CarryingReportedAmountFairValueDisclosure,us-gaap:FairValueMeasurementsNonrecurring | NA | NA | 44.0 | 43.8 | 50.3 | 50.3 | 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:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueMeasurementsNonrecurring | NA | NA | 2.3 | 4.6 | 8.3 | 8.3 | 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:IntangibleAssetsNetExcludingGoodwill | ▁▁▁▁▂▂▂▂▂▂▇▇▇████▇▇▃▃▃▃▃▃▃▃▃▃▃▃ | 156.8 | 158.3 | 163.2 | 164.5 | 174.3 | 175.1 | 195.3 | 193.9 | 197.6 | 199.0 | 352.1 | 359.3 | 365.3 | 378.0 | 380.5 | 387.8 | 389.4 | 362.6 | 365.142 | 231.179 | 233.329 | 235.508 | 237.376 | 219.017 | 221.112 | 223.314 | 225.515 | 227.716 | 229.917 | 232.118 | 234.319 | NA | NA | NA |
| us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueMeasurementsNonrecurring | NA | NA | NA | 6.4 | 8.0 | 8.0 | 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:DeferredTaxAssetsLiabilitiesNet | NA | NA | 40.2 | NA | NA | NA | 24.1 | 19.1 | 20.6 | 14.8 | 13.0 | 14.8 | 16.1 | 20.3 | 20.7 | 174.8 | NA | NA | 69.483 | NA | NA | NA | 126.198 | NA | NA | NA | 181.782 | NA | NA | NA | 206.921 | NA | NA | NA | |
| us-gaap:OperatingLeaseRightOfUseAsset | ▁▂▃▃▄▅████ | 4308.1 | 4348.7 | 4451.5 | 4475.8 | 4555.3 | 4602.3 | 4796.0 | 4794.9 | 4798.9 | 4809.2 | 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 | ▁▁▂▄▅▅▆▇▆▆▆▅▅▆▆▇▆█▇▆▆▆▆▅▅▄▄▄▄▄▄ | 261.2 | 273.1 | 304.6 | 419.8 | 455.8 | 450.2 | 503.0 | 537.9 | 520.4 | 493.7 | 505.5 | 438.3 | 438.6 | 505.9 | 475.9 | 544.7 | 509.1 | 595.1 | 533.792 | 518.229 | 508.371 | 483.067 | 523.525 | 433.873 | 436.201 | 419.1 | 417.604 | 415.251 | 410.629 | 400.766 | 402.504 | NA | NA | NA |
| us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueMeasurementsRecurring | █▂▁▁ | 12.1 | 10.7 | 10.6 | 10.5 | NA | NA | 11.9 | 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 |
| 2021-06-30 | 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AccountsPayableCurrent | ▂▃▃▅▆▄█▄▅▅▆▅▇▆█▆▆▇▇▂▃▂▃▂▃▂▂▁▂▂▃ | 235.2 | 264.9 | 298.8 | 376.9 | 436.1 | 337.1 | 543.3 | 361.6 | 423.2 | 382.8 | 452.6 | 395.1 | 535.8 | 454.2 | 569.6 | 469.1 | 477.8 | 510.4 | 501.761 | 261.447 | 298.456 | 240.807 | 313.025 | 212.195 | 268.891 | 210.326 | 262.635 | 181.727 | 258.69 | 223.984 | 268.163 | NA | NA | NA |
| us-gaap:LiabilitiesCurrent | ▆▆▆▆▇▆█▇▇▇▅▄▅▅▅▄▄▅▄▁▂▁▂▁▂▁▂▁▁▁▂ | 1558.4 | 1584.5 | 1578.5 | 1588.2 | 1711.2 | 1612.1 | 1933.2 | 1647.2 | 1713.9 | 1692.8 | 1328.1 | 1158.4 | 1243.4 | 1222.2 | 1409.4 | 1180.2 | 1146.6 | 1238.8 | 1189.19 | 595.157 | 620.362 | 583.907 | 712.154 | 558.273 | 616.916 | 554.06 | 636.377 | 503.327 | 583.09 | 553.808 | 657.996 | NA | NA | NA |
| us-gaap:LongTermDebtCurrent | ▆▆▆▆▆▆▆██▁▁ | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 21.4 | 21.4 | 15.2 | 15.2 | NA | NA | NA | 15.2 | NA | NA | NA | 15.195 | NA | NA | NA | 10.195 | NA | NA | NA | 15.873 | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:OperatingLeaseLiabilityCurrent | █▇▆▁▆▆▇▅▅▅ | 604.8 | 591.1 | 583.6 | 511.0 | 581.5 | 581.5 | 585.8 | 568.1 | 570.8 | 570.7 | 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 | ▅▅▄▅▄▅▆▇▆▇██▆▇▇▇▅▆▆▂▁▁▂▂▂▁▁▁▁▁▂ | 286.7 | 291.7 | 257.8 | 268.9 | 257.5 | 263.0 | 324.6 | 338.6 | 317.8 | 342.4 | 378.5 | 387.1 | 312.2 | 348.5 | 351.1 | 337.4 | 289.8 | 330.7 | 328.949 | 151.573 | 131.877 | 141.037 | 158.664 | 160.337 | 153.604 | 136.459 | 136.262 | 148.391 | 141.509 | 135.742 | 170.92 | NA | NA | NA |
| us-gaap:OtherLiabilitiesCurrent | NA | NA | 87.1 | NA | NA | NA | 114.1 | NA | NA | NA | 157.3 | NA | NA | NA | 146.6 | NA | NA | NA | 118.941 | NA | NA | NA | 23.129 | NA | NA | NA | 14.853 | NA | NA | NA | 19.831 | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:LiabilitiesNoncurrent us-gaap:EquityMethodInvestmentNonconsolidatedInvestee us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | NA | NA | 213.5 | NA | NA | NA | 260.5 | 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:LongTermDebt | ▄ | 5214.5 | NA | 5411.6 | 5448.3 | NA | NA | 4910.8 | NA | NA | NA | 4867.7 | 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:LongTermDebtNoncurrent | ▇▇██▇▇▆▆▆▆▆▆▅▅▅▅▅▅▄▁▁▁▁▁▁▁▁▁▁▁▂ | 5480.4 | 5439.4 | 5695.8 | 5803.8 | 5498.0 | 5020.8 | 4733.4 | 4710.1 | 4713.1 | 4737.7 | 4707.8 | 4840.3 | 4202.6 | 4244.1 | 4220.1 | 4277.4 | 4249.1 | 4180.0 | 3745.755 | 1843.339 | 1824.775 | 1851.16 | 1924.366 | 1746.996 | 1748.92 | 1771.628 | 1775.132 | 1780.27 | 1783.736 | 1932.13 | 2069.672 | NA | NA | NA |
| us-gaap:DeferredFinanceCostsNoncurrentNet | NA | NA | 8.3 | NA | NA | NA | 11.3 | NA | NA | NA | 6.7 | NA | NA | NA | 9.5 | NA | NA | NA | 7.707 | NA | NA | NA | 31.453 | NA | NA | NA | 13.129 | NA | NA | NA | 7.841 | NA | NA | NA | |
| us-gaap:DeferredIncomeTaxLiabilitiesNet | ▃▄▅▆▆▇▇██▇▆▆▆▇█▇▇▂▁ | 28.5 | 34.0 | 40.5 | 43.4 | 43.2 | 47.7 | 46.0 | 49.8 | 51.7 | 45.8 | 41.6 | 44.3 | 44.3 | 48.5 | 49.6 | 47.4 | 46.9 | 26.6 | 20.962 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent | NA | NA | 64.3 | NA | NA | NA | 59.9 | NA | NA | NA | 54.6 | NA | NA | NA | 62.7 | NA | NA | NA | 44.456 | NA | NA | NA | 42.196 | NA | NA | NA | 48.436 | NA | NA | NA | 30.177 | NA | NA | NA | |
| us-gaap:MinorityInterest | NA | 22.4 | 26.9 | 34.7 | 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:MinorityInterest us-gaap:DisposalGroupClassification,us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations,amch:ForumCinemasOu | 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:MinorityInterest us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations amch:ForumCinemasOu | NA | 22.4 | NA | 34.7 | 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:MinorityInterest us-gaap:StatementGeographical,us-gaap:DisposalGroupClassification,us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations amch:LithuaniaAndEstonia,us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations,amch:ForumCinemasOu | NA | NA | 26.9 | 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:OtherLiabilitiesNoncurrent | ▁▁▁▁▁▁▁▁▁▁████▇▇▆▆▆▄▄▄▃▃▃▃▃▃▃▃▃ | 188.6 | 207.1 | 241.3 | 240.6 | 220.0 | 212.0 | 195.9 | 190.0 | 192.0 | 188.2 | 963.1 | 980.7 | 963.0 | 937.5 | 903.8 | 847.7 | 746.6 | 726.5 | 706.562 | 513.857 | 492.393 | 484.668 | 462.626 | 438.944 | 437.402 | 419.61 | 419.717 | 394.584 | 387.049 | 378.837 | 370.946 | NA | NA | NA |
| us-gaap:OperatingLeaseLiabilityNoncurrent | ▆▆█▆▁▂▇▅▅▄ | 4888.6 | 4908.9 | 4957.8 | 4909.4 | 4744.4 | 4784.3 | 4913.8 | 4857.6 | 4852.0 | 4826.6 | 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 | ▅▁█▃ | 941.5 | 895.9 | 971.8 | 922.5 | 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 | ▃▁█▅ | 816.7 | 792.0 | 862.6 | 830.1 | 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 | ▅▁█▃ | 770.9 | 756.5 | 785.2 | 763.7 | 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 | ▃▁█▅ | 704.6 | 691.1 | 752.9 | 728.2 | 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 | ▂▁█▆ | 3768.1 | 3719.8 | 4371.1 | 4228.2 | 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 |
| 2021-06-30 | 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:StockholdersEquity | ▃▂▁▂▃▃▆▆▆▆▆▆▇▇▇███▇▇▇▇▇▇▇▇▇▇▇▇▇ | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214.2 | 1183.3 | 1325.1 | 1303.5 | 1397.6 | 1254.5 | 1969.9 | 2084.8 | 2112.4 | 2424.4 | 2476.7 | 2600.6 | 2009.654 | 1565.701 | 1552.846 | 1546.254 | 1538.703 | 1513.934 | 1521.052 | 1496.382 | 1512.732 | 1509.153 | 1524.429 | 1511.134 | 1507.47 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment | ▂▂▁▂▂▂▂▄▄▄▄▃▃▃▄▄▄▄▄▄▄▄▄▄▄▄▆█ | -17.6 | -17.9 | -21.4 | -16.4 | -16.6 | -17.2 | -17.3 | -1.6 | -1.7 | -1.7 | -1.8 | -7.4 | -7.5 | -7.2 | -6.6 | -4.1 | -4.1 | -3.5 | -3.569 | -3.276 | -3.281 | -3.285 | -3.289 | -4.597 | -3.493 | -3.499 | 5.564 | 19.573 | NA | NA | 20.967 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncome | ▄▄▅▃▃▁▄▂▃▄▄▅▅██▇▆▄▄▄▄▄▄▄▄▄▅▅ | 8.2 | -12.3 | 38.7 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26.0 | 33.5 | 140.5 | 125.6 | 105.8 | 72.1 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12.844 | 24.737 | NA | NA | 24.204 | NA | NA | NA |
| us-gaap:StockholdersEquity us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustment | ▅▄▆▃▃▁▄▁▃▃▄▅▅██▇▆▄▄▄▄▄▄▄▄▄▄▄ | 25.8 | 5.6 | 60.1 | -35.6 | -47.0 | -102.4 | -8.8 | -95.1 | -26.9 | -17.7 | 7.2 | 33.3 | 39.0 | 145.6 | 129.9 | 107.5 | 73.1 | -4.0 | -1.78 | 2.867 | 2.707 | 2.03 | 2.101 | 1.608 | 1.01 | 1.705 | 0.627 | 0.306 | NA | NA | -0.351 | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | ▃▂▁▂▃▄█ | -1404.7 | -2287.0 | -2858.2 | -2335.4 | -1575.4 | -1074.0 | 1214.2 | NA | NA | NA | 1397.6 | NA | NA | NA | 2112.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:EquityMethodInvestmentNonconsolidatedInvestee us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | NA | NA | 220.5 | NA | NA | NA | 699.7 | 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 us-gaap:StatementClassOfStock us-gaap:CommonClassA | NA | NA | NA | 0.6 | 0.5 | 0.5 | 0.5 | 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 us-gaap:StatementClassOfStock,us-gaap:StatementEquityComponents us-gaap:CommonClassA,us-gaap:CommonStock | █▇▁ | 5.1 | 4.5 | 1.8 | NA | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | NA | NA | NA | 0.5 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementClassOfStock,us-gaap:StatementEquityComponents us-gaap:CommonClassB,us-gaap:CommonStock | NA | NA | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | NA | NA | NA | 0.8 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncome | ▇▆█▄▃▁▅▂▅▅▇ | 8.2 | -12.3 | 38.7 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | NA | NA | NA | 125.6 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:AdditionalPaidInCapital | █▅▂▁▁▁▁▁▁▁▁ | 4847.4 | 3657.1 | 2465.6 | 2125.0 | 2007.3 | 2003.6 | 2001.9 | 2008.9 | 2006.8 | 2001.7 | 1998.4 | NA | NA | NA | 2241.6 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest | NA | 22.4 | 26.9 | 34.7 | 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 us-gaap:StatementEquityComponents us-gaap:Parent | ▃▂▁▂▃▄█████ | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214.2 | 1183.3 | 1325.1 | 1303.5 | 1397.6 | NA | NA | NA | 2112.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:RetainedEarnings | ▁▁▂▃▄▅█████ | -6265.4 | -5902.3 | -5335.3 | -4387.8 | -3463.7 | -2902.6 | -706.2 | -673.5 | -597.7 | -623.4 | -550.9 | NA | NA | NA | -207.9 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:TreasuryStockCommon | NA | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | NA | NA | NA | -48.2 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:CommonStockValue us-gaap:StatementClassOfStock us-gaap:CommonClassA | █▇▃▂▁▁▁▁▁▁▁▁▁▁▁▁▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁ | 5.1 | 4.5 | 1.8 | 0.6 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.6 | 0.6 | 0.342 | 0.215 | 0.215 | 0.215 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | 0.214 | NA | NA | NA |
| us-gaap:CommonStockValue us-gaap:StatementClassOfStock us-gaap:CommonClassB | NA | NA | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | 0.758 | NA | NA | NA | |
| us-gaap:AdditionalPaidInCapitalCommonStock | █▆▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▂▁▁▁▁▁▁▁▁▁▁▁▁ | 4847.4 | 3657.1 | 2465.6 | 2125.0 | 2007.3 | 2003.6 | 2001.9 | 2008.9 | 2006.8 | 2001.7 | 1998.4 | 1994.5 | 2247.0 | 2242.9 | 2241.6 | 2240.0 | 2240.3 | 2237.8 | 1627.384 | 1187.244 | 1185.539 | 1184.121 | 1183.218 | 1182.07 | 1179.782 | 1178.28 | 1172.515 | 1167.285 | 1168.829 | 1167.509 | 1161.152 | NA | NA | NA |
| us-gaap:RetainedEarningsAccumulatedDeficit | ▁▁▂▃▄▅▇▇▇▇▇▇▇▇▇████████████████ | -6265.4 | -5902.3 | -5335.3 | -4387.8 | -3463.7 | -2902.6 | -706.2 | -673.5 | -597.7 | -623.4 | -550.9 | -710.6 | -255.5 | -251.7 | -207.9 | 94.5 | 163.6 | 366.5 | 384.401 | 376.094 | 365.418 | 360.918 | 352.389 | 330.426 | 337.87 | 313.582 | 327.081 | 316.839 | 329.039 | 317.222 | 321.73 | NA | NA | NA |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax | ▄▄▅▃▃▁▄▂▃▄▄▅▅██▇▆▄▄▄▄▄▄▄▄▄▅▅▅▅▅▄▅▅ | 8.2 | -12.3 | 38.7 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26.0 | 33.5 | 140.5 | 125.6 | 105.8 | 72.1 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12.844 | 24.737 | 26.177 | 26.019 | 24.204 | 6.784 | 17.072 | 13.698 |
| us-gaap:MinorityInterest | NA | 22.4 | 26.9 | 34.7 | 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:MinorityInterest us-gaap:DisposalGroupClassification,us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations,amch:ForumCinemasOu | 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:MinorityInterest us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations amch:ForumCinemasOu | NA | 22.4 | NA | 34.7 | 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:MinorityInterest us-gaap:StatementGeographical,us-gaap:DisposalGroupClassification,us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations amch:LithuaniaAndEstonia,us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations,amch:ForumCinemasOu | NA | NA | 26.9 | 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:StockIssuedDuringPeriodValueNewIssues | █▁ | 989.2 | 581.6 | NA | 2.8 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0.0 | 0.0 | -0.9 | 617.5 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInOperatingActivities | ▂▁▁▁▂▃█▅▆▄▇▄▆▆█▆▄▆▇▅▆▅▇▅▆▅▆▅▅▄▆▅▅▅ | -233.8 | -312.9 | -357.9 | -355.7 | -231.9 | -184.0 | 368.8 | 56.6 | 152.2 | 1.4 | 224.4 | 1.7 | 131.7 | 165.4 | 329.6 | 119.3 | -62.7 | 172.5 | 220.4 | 77.352 | 111.077 | 22.871 | 258.275 | 16.31 | 171.352 | 21.563 | 178.712 | 12.342 | 107.823 | -1.575 | 152.677 | 71.161 | 97.622 | 35.882 |
| us-gaap:NetCashProvidedByUsedInInvestingActivities | ███▇▇▇▇▇▇▇▆█▇▇▇█▇▃▁▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇ | 13.5 | -16.0 | 0.2 | -23.3 | -44.1 | -87.4 | -167.7 | -127.1 | -122.8 | -98.5 | -202.9 | 67.2 | -66.7 | -114.8 | -149.9 | 66.7 | -138.5 | -743.5 | -1106.3 | -120.302 | -76.373 | -51.625 | -292.314 | -72.826 | -72.882 | -71.378 | -88.2 | -68.772 | -56.488 | -58.231 | -88.506 | -71.878 | -70.099 | -38.301 |
| us-gaap:NetCashProvidedByUsedInFinancingActivities | █▆▃▃▄▃▂▂▂▂▂▂▂▂▁▂▂▅▇▂▂▁▃▂▂▂▂▂▁▁▄▂▂▂ | 1212.2 | 854.7 | 247.8 | 296.6 | 473.5 | 312.4 | -40.0 | -18.4 | -20.6 | -33.9 | -39.5 | -37.4 | -55.5 | -62.4 | -128.7 | -60.2 | 6.9 | 674.3 | 1046.0 | -3.979 | -49.239 | -74.582 | 147.385 | -24.603 | -63.837 | -23.645 | -27.799 | -23.378 | -169.325 | -133.362 | 351.683 | -4.962 | 2.435 | -24.228 |
| us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect | █▅▁▂▃▂▃▂▂▁▂▂▂▂▂▃▁▃ | 997.5 | 520.7 | -107.4 | -79.6 | 198.6 | 34.3 | 164.9 | -90.6 | 6.0 | -128.8 | -20.3 | 16.9 | 14.9 | -5.8 | 26.9 | 131.5 | -176.5 | 106.2 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:AmortizationOfFinancingCosts | ▂█▁▁▂▂▂▂▂▂ | 3.4 | 12.1 | 2.6 | 3.2 | 4.3 | 4.1 | 4.0 | 4.0 | 3.4 | 4.4 | 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:DeferredIncomeTaxExpenseBenefit | ▄▄▄▄▄▅▄▄▄▄▄▄▄▄█▄▃▄▄▅▅▅▅▄▅▄▅▄▅▄▁▄▄▄ | -6.1 | -6.2 | -1.2 | -0.2 | -5.8 | 71.2 | -40.7 | -1.9 | 4.8 | 4.1 | -2.9 | -1.5 | -3.5 | 1.5 | 295.7 | -19.6 | -109.5 | -8.8 | -11.545 | 16.801 | 12.6 | 16.235 | 33.989 | -10.953 | 25.099 | 3.525 | 12.765 | 4.225 | 18.33 | -2.89 | -275.028 | 2.8 | 2.83 | 2.8 |
| us-gaap:DepreciationDepletionAndAmortization | ▅▆▇▆▆▆▆▆▆▆█▇▇▇█▇▇▇▃▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁ | 105.7 | 114.1 | 132.6 | 123.5 | 119.7 | 122.5 | 112.9 | 112.1 | 112.0 | 113.0 | 139.4 | 130.2 | 137.7 | 130.5 | 144.7 | 135.2 | 133.3 | 125.3 | 82.497 | 63.025 | 62.291 | 60.43 | 59.927 | 58.008 | 57.249 | 57.777 | 55.467 | 54.327 | 51.75 | 54.777 | 50.102 | 48.603 | 50.37 | 48.462 |
| us-gaap:IncreaseDecreaseInAccountsPayable | ▃▄▃▃▆▁█▃▅▃▆▁▅▂▇▄▄▃▇▃▅▃▆▃▅▃▆▃▅▃▆▃▅▄ | -56.0 | -11.9 | -55.2 | -66.2 | 114.8 | -169.8 | 206.0 | -65.5 | 41.0 | -76.7 | 105.4 | -149.0 | 65.1 | -107.1 | 151.0 | -18.3 | -28.1 | -69.9 | 138.44 | -70.081 | 34.611 | -81.48 | 111.206 | -75.598 | 64.752 | -58.998 | 77.573 | -68.514 | 28.959 | -51.71 | 88.905 | -62.828 | 43.035 | -4.897 |
| us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet | ▅▇▆▂▄▁▆▅▆▄▅▅▇▄▇▇▄▅▅▅▅▅▄▅▅▆▅▄█▄▅▃▇▆ | -2.2 | 11.9 | 5.6 | -19.3 | -6.0 | -23.5 | 4.3 | 1.0 | 7.7 | -5.5 | 1.5 | 1.0 | 8.1 | -4.5 | 8.1 | 13.4 | -4.8 | -0.4 | -1.21 | -0.526 | -1.419 | -1.059 | -4.294 | -0.402 | -0.436 | 3.718 | -2.044 | -4.408 | 16.534 | -8.016 | 0.285 | -12.741 | 9.741 | 2.823 |
| us-gaap:NetCashProvidedByUsedInOperatingActivities | ▂▁▁▁▂▃█▅▆▄▇▄▆▆█▆▄▆▇▅▆▅▇▅▆▅▆▅▅▄▆▅▅▅ | -233.8 | -312.9 | -357.9 | -355.7 | -231.9 | -184.0 | 368.8 | 56.6 | 152.2 | 1.4 | 224.4 | 1.7 | 131.7 | 165.4 | 329.6 | 119.3 | -62.7 | 172.5 | 220.4 | 77.352 | 111.077 | 22.871 | 258.275 | 16.31 | 171.352 | 21.563 | 178.712 | 12.342 | 107.823 | -1.575 | 152.677 | 71.161 | 97.622 | 35.882 |
| us-gaap:NetIncomeLoss | ▆▆▅▅▆▁▇▇█▇█▇██▇▇▇█████ | -343.6 | -566.9 | -945.8 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49.4 | -130.2 | 170.6 | -100.4 | 22.2 | 17.7 | -276.4 | -42.7 | -176.5 | 8.4 | 29.0 | 30.4 | 24.0 | 28.3 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest | NA | -0.3 | 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:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:Parent | NA | -566.9 | NA | -905.8 | -561.2 | -2176.3 | NA | -54.8 | 49.4 | -130.2 | 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:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings | NA | -566.9 | NA | -905.8 | -561.2 | -2176.3 | NA | -54.8 | 49.4 | -130.2 | NA | -100.4 | 22.2 | 17.7 | NA | -42.7 | -176.5 | 8.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:ProfitLoss | ▆▆▅▅▆▁▇▇█▇█▇██▇▇▇█ | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49.4 | -130.2 | 170.6 | -100.4 | 22.2 | 17.7 | -276.4 | -42.7 | -176.5 | 8.4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:ProfitLoss us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName amch:DigitalCinemaImplementationPartnersLLC | NA | NA | NA | -30.6 | NA | NA | NA | 22.3 | 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:ShareBasedCompensation | ▆▅█▄▄▄▁▄▅▄▄▄▄▄▄▃▄▃▃▄▄▃▃▄▄▅▅▃▄▅ | 8.4 | 5.4 | 15.9 | 3.1 | 3.7 | 2.7 | -7.1 | 2.1 | 5.4 | 4.0 | 4.0 | 4.1 | 4.0 | 2.8 | 1.8 | -0.1 | 3.9 | 0.1 | 0.346 | 1.705 | 1.717 | 1.087 | 1.103 | 2.199 | 1.439 | 5.739 | 5.221 | -1.596 | 1.311 | 6.357 | NA | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInInvestingActivities | ███▇▇▇▇▇▇▇▆█▇▇▇█▇▃▁▇▇▇▆▇▇▇▇▇▇▇▇▇▇▇ | 13.5 | -16.0 | 0.2 | -23.3 | -44.1 | -87.4 | -167.7 | -127.1 | -122.8 | -98.5 | -202.9 | 67.2 | -66.7 | -114.8 | -149.9 | 66.7 | -138.5 | -743.5 | -1106.3 | -120.302 | -76.373 | -51.625 | -292.314 | -72.826 | -72.882 | -71.378 | -88.2 | -68.772 | -56.488 | -58.231 | -88.506 | -71.878 | -70.099 | -38.301 |
| us-gaap:PaymentsToAcquireProductiveAssets | ▁▁▁▂▂▄▇▅▅▅█▆▆▅▆▆▆▇▇▅▄▃▅▃▃▃▄▃▃▃▄▃▃▂ | 17.9 | 11.9 | 17.8 | 29.3 | 35.0 | 91.7 | 169.9 | 118.3 | 115.1 | 114.8 | 201.4 | 133.8 | 133.8 | 107.3 | 159.1 | 149.7 | 156.7 | 161.3 | 165.114 | 116.3 | 82.6 | 57.657 | 117.849 | 71.817 | 74.167 | 69.59 | 87.766 | 67.76 | 59.609 | 55.599 | 85.462 | 70.666 | 65.345 | 39.35 |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:NetCashProvidedByUsedInFinancingActivities | █▆▃▃▄▃▂▂▂▂▂▂▂▂▁▂▂▅▇▂▂▁▃▂▂▂▂▂▁▁▄▂▂▂ | 1212.2 | 854.7 | 247.8 | 296.6 | 473.5 | 312.4 | -40.0 | -18.4 | -20.6 | -33.9 | -39.5 | -37.4 | -55.5 | -62.4 | -128.7 | -60.2 | 6.9 | 674.3 | 1046.0 | -3.979 | -49.239 | -74.582 | 147.385 | -24.603 | -63.837 | -23.645 | -27.799 | -23.378 | -169.325 | -133.362 | 351.683 | -4.962 | 2.435 | -24.228 |
| us-gaap:PaymentsOfDividends | NA | NA | 2.2 | 0.0 | 0.0 | 4.3 | 20.7 | 20.8 | 20.8 | 21.8 | 20.7 | 186.0 | 25.6 | 25.8 | 25.9 | 78.7 | 52.5 | 26.2 | 20.546 | 19.639 | 19.639 | 19.803 | 19.596 | 19.711 | 19.48 | 19.821 | 19.501 | 19.514 | NA | NA | NA | NA | NA | NA |
| 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 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:ConsolidatedEntities,us-gaap:DebtInstrument,us-gaap:SubsequentEventType amch:OdeonCinemasGroupLimited,amch:FourHundredMillionTermLoanFacility,us-gaap:SubsequentEvent | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:CreditFacility amch:FirstLienNotesDue2025 | ████▁ | 1.05e-05 | 1.05e-05 | 1.05e-05 | 1.05e-05 | 1.05e-07 | NA | 1.05e-07 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:CreditFacility amch:OdeonRevolvingCreditFacilityDue2022Rate26 | NA | NA | 2.6e-06 | NA | 2.5999999999999998e-08 | 2.5999999999999998e-08 | 2.5999999999999998e-08 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:CreditFacility amch:OdeonRevolvingCreditFacilityDue2022Rate317 | NA | NA | 2.5785e-06 | NA | 3.17e-08 | 3.17e-08 | 3.17e-08 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:CreditFacility amch:SecondLienNotesDue2026 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:CreditFacility amch:SeniorSecuredCreditFacilityTermLoanDue2026 | ▁▆█ | 3.0855e-06 | 3.195e-06 | 3.23e-06 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:FirstLienNotesDue2026 | NA | NA | NA | 1.05e-05 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotes5.75PercentDue2025 | ▄▄▄ | 5.75e-06 | 5.75e-06 | 5.75e-06 | NA | NA | 5.7500000000000005e-08 | 5.7500000000000005e-08 | NA | 5.7500000000000005e-08 | 5.7500000000000005e-08 | 5.7500000000000005e-08 | 5.7500000000000005e-08 | NA | NA | 5.7500000000000005e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | NA | 5.7500000000000005e-08 | 5.7500000000000005e-08 | 5.7500000000000005e-08 | 5.7500000000000005e-08 | 5.7500000000000005e-08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotes5.875PercentDue2026 | ▄▄▄ | 5.875e-06 | 5.875e-06 | 5.875e-06 | NA | NA | 5.8749999999999993e-08 | 5.8749999999999993e-08 | NA | 5.8749999999999993e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | NA | NA | 5.8749999999999993e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | 5.8749999999999993e-08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotes6.125PercentDue2027 | ▄▄▄ | 6.125e-06 | 6.125e-06 | 6.125e-06 | NA | NA | 6.125e-08 | 6.125e-08 | NA | 6.125e-08 | 6.125e-08 | 6.125e-08 | 6.125e-08 | NA | NA | 6.125e-08 | 6.125e-08 | 6.125e-08 | 6.125e-08 | 6.125e-08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotes6.375PercentDue2024 | ▄▄▄ | 6.375e-06 | 6.375e-06 | 6.375e-06 | NA | NA | 6.375e-08 | 6.375e-08 | NA | 6.375e-08 | 6.375e-08 | 6.375e-08 | 6.375e-08 | NA | NA | 6.375e-08 | 6.375e-08 | 6.375e-08 | NA | 6.375e-08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotesDue5.75Percent2025 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotesDue5.875Percent2026 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotesDue6.125Percent2027 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorSubordinatedNotesDue6.375Percent2024 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument amch:SeniorUnsecuredConvertibleNotesDue2024 | NA | NA | 2.95e-06 | 2.95e-06 | NA | 2.95e-08 | 2.95e-08 | NA | 2.95e-08 | 2.95e-08 | 2.95e-08 | 2.95e-08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument,us-gaap:SubsequentEventType amch:New10.500SeniorSecuredNotesDue2026,us-gaap:SubsequentEvent | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument,us-gaap:SubsequentEventType amch:SeniorSubordinatedNotesDue6.375Percent2024,us-gaap:SubsequentEvent | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:CreditFacility srt:Maximum,us-gaap:RevolvingCreditFacility | NA | NA | 2.74e-06 | 2.76e-06 | 2.87e-08 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:CreditFacility srt:Minimum,us-gaap:RevolvingCreditFacility | NA | NA | 2.65e-06 | 2.65e-06 | 2.36e-08 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:DebtInstrument srt:Maximum,amch:SecondLienSubordinatedSecuredNotesDue2026 | NA | NA | NA | 1.2e-05 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:DebtInstrument srt:Minimum,amch:SecondLienSubordinatedSecuredNotesDue2026 | NA | NA | NA | 1e-05 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:DebtInstrument,us-gaap:SubsequentEventType srt:Maximum,amch:SecondLienSubordinatedSecuredNotesDue2026,us-gaap:SubsequentEvent | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:DebtInstrument,us-gaap:SubsequentEventType srt:Minimum,amch:SecondLienSubordinatedSecuredNotesDue2026,us-gaap:SubsequentEvent | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:LongtermDebtType srt:Maximum,amch:DebtAgreementWithMudrickCapitalManagementLp | NA | NA | 1.7e-05 | 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:DebtInstrumentInterestRateStatedPercentage us-gaap:Range,us-gaap:LongtermDebtType srt:Minimum,amch:DebtAgreementWithMudrickCapitalManagementLp | NA | NA | 1.5e-05 | 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 |
| 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 | 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 |
| Value | 5100000.0 | 4500000.0 | 1800000.0 | 600000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 600000.0 | 600000.0 | 342000.0 | 215000.0 | 215000.0 | 215000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 |
| 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 | 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 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 |
| Percentage of CommonStockValue | 27.8 | 83.3 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 160.0 | 160.0 | 160.0 | 160.0 | 133.3 | 133.3 | 221.6 | 352.6 | 352.6 | 352.6 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 |
| 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 |
| Percentage of Assets us-gaap:CommonClassB | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-01-25 | 2020-10-20 |
| Value | 50 | 15 |
| Percentage of CommonStockSharesAuthorized | 100.0 | 100.0 |
| Period End | 2021-04-27 | 2020-10-20 |
| Value | 43 | 15 |
| Percentage of CommonStockSharesAuthorized | 0.0 | 100.0 |
| Period End | 2021-04-27 |
| Value | 43 |
| Percentage of CommonStockSharesAuthorized | 0.0 |
| Period End | 2021-06-30 | 2021-01-25 | 2020-12-11 | 2020-11-10 | 2020-10-20 | 2020-09-24 |
| Value | 241 | 50 | 178 | 20 | 15 | 15 |
| Percentage of CommonStockSharesAuthorized | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 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 | 480 | 400 | 152 | 107 | 104 | 104 | 103 | 103 | 135 | 103 | 135 | 123 | 128 | 128 | 129 | 131 | 131 | 121 | 98 | 98 | 98 | 98 | 98 | 97 | 97 | 0.097628 | 0.09762812 | 0.09739009 | 78 | 0.076 | 0.07600003 | 0.07600003 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 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 | 480 | 400 | 152 | 107 | 104 | 104 | 103 | 103 | 103 | 103 | 103 | 123 | 128 | 128 | 129 | 131 | 131 | 121 | 98 | 98 | 98 | 97 | 97 | 97 | 97 | 0.097506 | 0.09750668 | 0.09739009 | 78 | 0.076 | 0.07600003 | 0.07600003 |
| 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 | 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 | 2019-09-30 | 2019-03-31 | 2018-09-30 |
| Value | 31 | 34 | 31 | 31 | 31 | 5.9 |
| Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | -0.71 | -1.42 | -6.21 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.48 | -1.25 | 1.65 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.29 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.31 | 0.08 | 0.32 | -0.05 | 3.58 | 0.44 | 0.81 | -0.13 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | -0.71 | -1.42 | -6.21 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.17 | -1.25 | 0.43 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.29 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.3 | 0.08 | 0.32 | -0.05 | 3.58 | 0.44 | 0.81 | -0.13 |
| 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 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | -0.71 | -1.42 | -4.59 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.48 | -1.25 | 1.39 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.29 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.31 | 0.08 | 0.32 | -0.05 | 3.62 | 0.45 | 0.81 | -0.2 |
| Percentage of IncomeLossFromContinuingOperationsPerBasicShare | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | -0.71 | -1.42 | -4.59 | -8.41 | -5.38 | -20.88 | -0.13 | -0.53 | 0.17 | -1.25 | 0.89 | -0.82 | 0.17 | 0.14 | -2.14 | -0.33 | -1.35 | 0.07 | 0.29 | 0.31 | 0.24 | 0.29 | 0.42 | 0.12 | 0.45 | 0.06 | 0.3 | 0.08 | 0.32 | -0.05 | 3.62 | 0.45 | 0.81 | -0.2 |
| Percentage of IncomeLossFromContinuingOperationsPerDilutedShare | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 | 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 | 2013-03-31 |
| Value | 8.4 | 5.4 | 3.7 | 2.7 | 1.087 | 1.103 | 2.199 | 1.439 | 5.739 | 5.221 | -1.596 | 1.311 | 6.357 | 12 | 0.0 | 0.0 | 0.0 |
| Percentage of AllocatedShareBasedCompensationExpense | 100.0 | 100.0 | 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 1.9 | 3.6 | 19.6 | 0.3 | 0.1 | 0.1 | 0.3 | 0.2 | 0.9 | 0.7 | -0.3 | 0.2 | 1.0 | 1.7 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 |
| Value | 3.4 |
| Percentage of AllocatedShareBasedCompensationExpense | 40.5 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:PerformanceStockUnits | 0.0 |
| Period End | 2021-06-30 | 2020-06-30 |
| Value | 1.5 | 0.7 |
| Percentage of AllocatedShareBasedCompensationExpense | 17.9 | 18.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.3 | 3.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:SpecialPerformanceStockUnit | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2020-06-30 |
| Value | 3.5 | 3.0 |
| Percentage of AllocatedShareBasedCompensationExpense | 41.7 | 81.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.8 | 15.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RestrictedStockUnitsRSU | 0.0 | 0.0 |
| Period End | 2021-03-31 | 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 | 2015-09-30 | 2015-06-30 |
| Value | 5.4 | 2.7 | -7.1 | 2.1 | 5.4 | 4.0 | 4.0 | 4.2 | 4.0 | 2.8 | 1.8 | -0.1 | 3.9 | 0.1 | 2.291 | 1.705 | 1.717 | 1.1 | 2.199 | 1.439 |
| Percentage of AllocatedShareBasedCompensationExpense | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 101.2 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.6 | 0.3 | -0.5 | 0.2 | 0.4 | 0.3 | 0.3 | 0.3 | 0.3 | 0.2 | 0.1 | -0.0 | 0.3 | 0.0 | 0.2 | 0.2 | 0.2 | 0.1 | 0.3 | 0.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:GeneralAndAdministrativeExpense | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-03-31 | 2020-03-31 |
| Value | 5.4 | 2.7 |
| Percentage of AllocatedShareBasedCompensationExpense | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.6 | 0.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AdditionalPaidInCapital | 0.0 | 0.0 |
| Period End | 2021-03-31 |
| Value | 5.4 |
| Percentage of AllocatedShareBasedCompensationExpense | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent | 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 | 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 | -323.1 | -617.9 | -855.3 | -894.2 | -505.2 | -2269.8 | 57 | -122.9 | 40 | -155.1 | 150 | -107.9 | -85.0 | 28 | -256.6 | -9.0 | -100.0 | 6.5 | 24 | 30 | 24 | 26 | 43 | 10 | 42 | -2.478 | 17 | 5.936 | 31 | -2.693 | 297 | 23 | 64 | -6.004 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | -72.7 | -416.7 | -526.3 | -748.3 | -2673.0 | -241.1 | 3.9 | -9.3 | 2.7 | -12.9 | 10.6 | -8.8 | -6.1 | 2.0 | -18.1 | -0.8 | -8.3 | 0.5 | 2.6 | 4.0 | 3.2 | 3.4 | 5.5 | 1.5 | 5.2 | -0.4 | 2.5 | 0.9 | 4.3 | -0.4 | 41.7 | 3.3 | 8.5 | -1.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -400000.0 | -500000.0 |
| Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.1 | -0.3 |
| 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 |
| Value | -323500000.0 | -618400000.0 | -855400000.0 | -894200000.0 | -505200000.0 | -2269800000.0 | 57100000.0 | -122900000.0 |
| Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -72.7 | -417.0 | -526.4 | -748.3 | -2673.0 | -241.1 | 3.9 | -9.3 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 |
| Value | 98 | 22 | 24 | 26 | 0.2 | 271 | 434 | 416 | 482 | 365 | 433 | 378 | 471 | 426 | 440 | 364 |
| Percentage of CostOfGoodsAndServicesSold | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 22.2 | 14.8 | 14.9 | 22.3 | 1.1 | 28.9 | 30.0 | 31.7 | 32.0 | 30.4 | 30.7 | 31.0 | 34.1 | 30.8 | 31.1 | 30.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Admission | 42.4 | 31.7 | 0.0 | 42.3 | 22.2 | 47.8 | 0.0 | 52.3 | 53.9 | 49.9 | 0.0 | 50.4 | 52.6 | 48.7 | 0.0 | 48.4 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 |
| Value | 26 | 9.7 | 22 | 8.8 | 4.5 | 53 | 73 | 67 | 76 | 61 | 68 | 63 | 72 | 66 | 69 | 60 |
| Percentage of CostOfGoodsAndServicesSold | 26.6 | 44.1 | 91.3 | 33.1 | 2250.0 | 19.7 | 16.9 | 16.1 | 15.8 | 16.8 | 15.9 | 16.8 | 15.3 | 15.5 | 15.8 | 16.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 5.9 | 6.5 | 13.6 | 7.4 | 23.8 | 5.7 | 5.1 | 5.1 | 5.1 | 5.1 | 4.9 | 5.2 | 5.2 | 4.8 | 4.9 | 5.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:FoodAndBeverage | 16.3 | 19.4 | 0.0 | 30.2 | 1125.0 | 18.5 | 0.0 | 16.0 | 15.5 | 16.7 | 0.0 | 16.5 | 16.2 | 16.3 | 0.0 | 16.8 |
| 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 | 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 | 741 | 576 | 1132 | 794 | 490 | 2927 | 1404 | 1296 | 1400 | 1234 | 1326 | 1243 | 1352 | 1273 | 1346 | 1183 | 1221 | 1228 | 893 | 714 | 708 | 706 | 708 | 653 | 726 | 621 | 651 | 605 | 658 | 605 | 679 | 638 | 684 | 558 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 166.7 | 388.5 | 696.7 | 665.2 | 2595.2 | 311.0 | 97.0 | 98.4 | 93.0 | 102.8 | 93.8 | 101.8 | 97.8 | 92.1 | 95.0 | 100.4 | 101.6 | 95.8 | 96.5 | 91.6 | 92.7 | 92.3 | 90.4 | 94.8 | 88.5 | 95.1 | 91.5 | 95.5 | 90.6 | 97.2 | 95.3 | 91.7 | 89.8 | 96.6 |
| Period End | 2020-09-30 | 2019-09-30 |
| Value | 31 | 17 |
| Percentage of CostsAndExpenses | 4.0 | 1.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 26.5 | 1.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:DigitalCinemaImplementationPartnersLLC | 0.0 | 0.0 |
| Period End | 2021-05-31 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 5500000.0 | 300000.0 | -1600000.0 | 2800000.0 |
| Percentage of DisposalGroupNotDiscontinuedOperationGainLossOnDisposal | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.2 | -1.0 | 2.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations amch:ForumCinemasOu | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 93 |
| Percentage of GainsLossesOnExtinguishmentOfDebt | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 57.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OtherExpense | 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 | 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 | -349.2 | -574.0 | -952.9 | -901.2 | -567.3 | -2108.1 | -46.9 | -55.0 | 54 | -124.5 | 171 | -89.3 | 19 | 22 | 14 | -60.3 | -286.1 | -0.8 | 12 | 50 | 40 | 46 | 64 | 21 | 67 | 10 | 41 | 12 | 51 | -7.942 | 8.368 | 37 | 66 | -12.137 |
| 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 | 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 | -78.5 | -387.1 | -586.4 | -754.1 | -3001.6 | -223.9 | -3.2 | -4.2 | 3.6 | -10.4 | 12.1 | -7.3 | 1.4 | 1.6 | 1.0 | -5.1 | -23.8 | -0.1 | 1.3 | 6.5 | 5.3 | 6.1 | 8.3 | 3.1 | 8.2 | 1.5 | 5.8 | 1.9 | 7.1 | -1.3 | 1.2 | 5.4 | 8.7 | -2.1 |
| 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 | 2014-03-31 | 2013-03-31 |
| Value | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | -4.842 | -15.237 |
| Percentage of IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.4 | -382.5 | -582.2 | -758.0 | -2969.3 | -231.2 | -0.9 | -4.2 | -0.8 | -2.6 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -0.4 | -0.3 |
| Percentage of IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest | 0.1 | 0.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.1 | -0.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -343.6 | -566.9 |
| Percentage of IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest | 99.9 | 99.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.3 | -382.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -343.6 | -566.9 |
| Percentage of IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest | 99.9 | 99.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.3 | -382.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings | 0.0 | 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 | 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 | -5.2 | -6.8 | -6.8 | 4.6 | -6.1 | 68 | -33.4 | -0.2 | 5.4 | 5.7 | 0.4 | 11 | -2.6 | 4.7 | 290 | -17.6 | -109.6 | -9.2 | 19 | 20 | 16 | 18 | 23 | 9.08 | 23 | 3.93 | 11 | 4.71 | 20 | -3.1 | -274.243 | 3.43 | 4.33 | 3.1 |
| 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 | 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 | -1.2 | -4.6 | -4.2 | 3.8 | -32.3 | 7.2 | -2.3 | -0.0 | 0.4 | 0.5 | 0.0 | 0.9 | -0.2 | 0.3 | 20.5 | -1.5 | -9.1 | -0.7 | 2.1 | 2.6 | 2.1 | 2.4 | 3.0 | 1.3 | 2.8 | 0.6 | 1.7 | 0.7 | 2.8 | -0.5 | -38.5 | 0.5 | 0.6 | 0.5 |
| 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 |
| Value | 0.1 | -0.2 | 0.2 | 0.0 | 0.0 | -0.1 | 0.2 | 0.1 | 0.1 |
| Percentage of IncomeTaxExpenseBenefit | -1.9 | 2.9 | -2.9 | 0.0 | -0.0 | -0.1 | -0.6 | -50.0 | 1.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | -0.1 | 0.1 | 0.0 | 0.0 | -0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:AttributableEarningsBeforeInterestTaxesDepreciationAmortization | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 | -2.9 | 9.0 | 0.9 | 0.9 | 7.0 | 1.7 | -1.8 | 2.1 | -4.5 | 2.5 | 9.6 | 1.5 | 3.9 | 4.5 | 1.3 | 3.1 | 5.5 | 1.0 | 0.146 | 0.502 | 3.284 | 0.806 | 6.379 | 0.102 | -1.635 | 0.505 | -0.806 | 0.015 | 0.566 | 1.309 | 1.149 | -0.339 |
| Percentage of IncomeTaxesPaidNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | -0.7 | 6.1 | 0.6 | 0.8 | 37.0 | 0.2 | -0.1 | 0.2 | -0.3 | 0.2 | 0.7 | 0.1 | 0.3 | 0.3 | 0.1 | 0.3 | 0.5 | 0.1 | 0.0 | 0.1 | 0.4 | 0.1 | 0.8 | 0.0 | -0.2 | 0.1 | -0.1 | 0.0 | 0.1 | 0.2 | 0.2 | -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 | 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 | 98 | 162 | 88 | 94 | 91 | 82 | 85 | 85 | 86 | 83 | 93 | 84 | 82 | 82 | 70 | 71 | 69 | 61 | 40 | 26 | 27 | 27 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 22.2 | 109.8 | 54.5 | 78.9 | 482.5 | 8.8 | 5.9 | 6.5 | 5.7 | 7.0 | 6.6 | 6.9 | 6.0 | 6.0 | 5.0 | 6.1 | 5.8 | 4.8 | 4.4 | 3.4 | 3.5 | 3.5 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2019-09-30 | 2019-06-30 |
| Value | 0.2 | 0.0 | 0.1 | 0.0 | 0.1 |
| Percentage of InterestExpense | 0.2 | 0.0 | 0.1 | 0.0 | 0.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 0.0 | 0.1 | 0.0 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:AttributableEarningsBeforeInterestTaxesDepreciationAmortization | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 | 88 | 151 | 77 | 82 | 79 | 71 | 74 | 73 | 74 | 71 | 74 | 64 | 62 | 61 | 59 | 60 | 59 | 51 | 36 | 24 | 24 | 24 | 23 | 22 | 24 | 26 | 26 | 26 | 27 | 29 | 32 | 32 | 32 | 33 |
| Percentage of InterestExpenseDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 19.8 | 102.2 | 47.6 | 69.3 | 421.2 | 7.6 | 5.1 | 5.6 | 4.9 | 5.9 | 5.2 | 5.3 | 4.5 | 4.5 | 4.2 | 5.2 | 5.0 | 4.0 | 3.9 | 3.2 | 3.3 | 3.2 | 3.0 | 3.3 | 3.0 | 4.0 | 3.7 | 4.2 | 3.9 | 4.8 | 4.5 | 4.6 | 4.2 | 5.7 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 70 |
| Percentage of InterestExpenseDebt | 0.0 | 46.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 47.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:ConvertibleNotesDue2026 | 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 | 2018-09-14 | 2018-09-30 |
| Value | 7.4 | 7.8 | 8.3 | 8.3 | 8.4 | 8.2 | 8.0 | 8.0 | 9.7 | 32 | 1.5 |
| Percentage of InterestExpenseDebt | 9.6 | 9.4 | 10.4 | 11.6 | 11.3 | 11.2 | 10.8 | 11.2 | 13.1 | 2.3 | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.6 | 6.5 | 43.9 | 0.9 | 0.6 | 0.6 | 0.5 | 0.7 | 0.0 | 0.0 | 0.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:SeniorUnsecuredConvertibleNotesDue2024 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-01-27 |
| Value | 70 |
| Percentage of InterestExpenseDebt | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:ConvertibleNotesDue2026 us-gaap:SubsequentEvent | 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 | 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 | -343.6 | -566.9 | -945.8 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49 | -130.2 | 170 | -100.4 | 22 | 17 | -276.4 | -42.7 | -176.5 | 8.4 | 29 | 30 | 24 | 28 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.3 | -382.3 | -582.0 | -758.0 | -2969.3 | -231.2 | -0.9 | -4.2 | 3.3 | -10.8 | 12.1 | -8.2 | 1.6 | 1.3 | -19.5 | -3.6 | -14.7 | 0.7 | 3.1 | 3.9 | 3.1 | 3.7 |
| Period End | 2021-03-31 |
| Value | -0.3 |
| Percentage of NetIncomeLoss | 0.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest | 0.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -566.9 | -905.8 | -561.2 | -2176.3 | -54.8 | 49 | -130.2 |
| Percentage of NetIncomeLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -382.3 | -758.0 | -2969.3 | -231.2 | -4.2 | 3.3 | -10.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | -566.9 | -905.8 | -561.2 | -2176.3 | -54.8 | 49 | -130.2 | -100.4 | 22 | 17 | -42.7 | -176.5 | 8.4 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -382.3 | -758.0 | -2969.3 | -231.2 | -4.2 | 3.3 | -10.8 | -8.2 | 1.6 | 1.3 | -3.6 | -14.7 | 0.7 |
| 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 | 2021-06-30 | 2021-03-31 |
| Value | -400000.0 | -300000.0 |
| Percentage of NetIncomeLossAttributableToNoncontrollingInterest | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.1 | -0.2 |
| 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 | 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 | -4.0 | 2.3 | -11.8 | 1.8 | -1.5 | 2.1 | 4.7 | 5.3 | 2.3 | 2.5 | 7.8 | 6.6 | 5.7 | 3.7 | 8.1 | 3.7 | 3.5 | 5.3 | 7.117 | 5.8 | 3.8 | 3.4 |
| Percentage of OperatingExpenses | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 1.6 | -7.3 | 1.5 | -7.9 | 0.2 | 0.3 | 0.4 | 0.2 | 0.2 | 0.6 | 0.5 | 0.4 | 0.3 | 0.6 | 0.3 | 0.3 | 0.4 | 0.8 | 0.7 | 0.5 | 0.4 |
| 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 | 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 | -296.6 | -427.8 | -969.6 | -675.4 | -471.6 | -1986.1 | 43 | 20 | 105 | -33.7 | 87 | -21.9 | 89 | 109 | 70 | -4.3 | -19.6 | 55 | 32 | 65 | 55 | 59 | 75 | 35 | 94 | 32 | 60 | 28 | 68 | 17 | 33 | 57 | 77 | 19 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -66.7 | -288.5 | -596.7 | -565.2 | -2495.2 | -211.0 | 3.0 | 1.6 | 7.0 | -2.8 | 6.2 | -1.8 | 6.5 | 7.9 | 5.0 | -0.4 | -1.6 | 4.3 | 3.5 | 8.4 | 7.3 | 7.7 | 9.6 | 5.2 | 11.5 | 4.9 | 8.5 | 4.5 | 9.4 | 2.8 | 4.7 | 8.3 | 10.2 | 3.4 |
| 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 | 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 |
| Value | 42 | 17 | 116 | -125.0 | 6.6 | -26.9 | -8.3 | 1.3 | 23 | -29.8 | 165 | -54.1 | -2.2 | -1.2 | -0.6 | 0.6 | -1.0 | 2.7 | 0.441 | -0.079 | 0.11 | -1.411 | 0.0 | -9.273 | -0.053 | 0.011 |
| Percentage of OtherNonoperatingIncomeExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 9.6 | 11.7 | 71.6 | -104.6 | 34.9 | -2.9 | -0.6 | 0.1 | 1.6 | -2.5 | 11.7 | -4.4 | -0.2 | -0.1 | -0.0 | 0.1 | -0.1 | 0.2 | 0.0 | -0.0 | 0.0 | -0.2 | 0.0 | -1.1 | -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 | 0.0 | 5.9 | 6.4 | 20 | 32 | 5.7 | 7.1 | 15 |
| Percentage of OtherNonoperatingIncomeExpense | 0.0 | -4.7 | 97.0 | -74.7 | -392.8 | 438.5 | 30.3 | -50.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.0 | 4.9 | 33.9 | 2.1 | 2.3 | 0.4 | 0.5 | 1.3 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:SeniorUnsecuredConvertibleNotesDue2024 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49 | -130.2 | 170 | -100.4 | 22 | 17 | -276.4 | -42.7 | -176.5 | 8.4 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.4 | -382.5 | -582.2 | -758.0 | -2969.3 | -231.2 | -0.9 | -4.2 | 3.3 | -10.8 | 12.1 | -8.2 | 1.6 | 1.3 | -19.5 | -3.6 | -14.7 | 0.7 |
| Period End | 2020-09-30 | 2019-09-30 |
| Value | -30.6 | 22 |
| Percentage of ProfitLoss | 3.4 | -40.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -25.6 | 1.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:DigitalCinemaImplementationPartnersLLC | 0.0 | 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 | 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 | 444 | 148 | 162 | 119 | 18 | 941 | 1447 | 1316 | 1506 | 1200 | 1413 | 1221 | 1383 | 1383 | 1416 | 1178 | 1202 | 1281 | 926 | 779 | 763 | 766 | 783 | 688 | 821 | 653 | 712 | 633 | 726 | 622 | 712 | 695 | 762 | 577 |
| 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 |
| 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 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 50 | 28 | 37 | 27 | 17 | 85 | 132 | 99 | 118 | 100 | 115 | 85 | 100 | 102 | 104 | 63 | 66 | 66 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 11.3 | 19.4 | 23.0 | 23.0 | 93.1 | 9.1 | 9.1 | 7.6 | 7.8 | 8.3 | 8.2 | 7.0 | 7.3 | 7.4 | 7.4 | 5.4 | 5.6 | 5.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 11.3 | 19.4 | 23.0 | 23.0 | 93.1 | 9.1 | 9.1 | 7.6 | 7.8 | 8.3 | 8.2 | 7.0 | 7.3 | 7.4 | 7.4 | 5.4 | 5.6 | 5.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:TotalOtherProductAndService | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 233 | 69 | 80 | 62 | 0.9 | 568 | 877 | 797 | 895 | 731 | 862 | 751 | 896 | 875 | 897 | 753 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 52.4 | 46.9 | 49.4 | 52.6 | 4.8 | 60.3 | 60.6 | 60.5 | 59.5 | 60.9 | 61.0 | 61.5 | 64.8 | 63.2 | 63.3 | 63.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 52.4 | 46.9 | 49.4 | 52.6 | 4.8 | 60.3 | 60.6 | 60.5 | 59.5 | 60.9 | 61.0 | 61.5 | 64.8 | 63.2 | 63.3 | 63.9 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Admission | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 19 | 16 | 19 | 16 | 14 | 29 | 40 | 32 | 35 | 34 | 39 | 31 | 33 | 37 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.4 | 11.4 | 12.1 | 14.1 | 75.7 | 3.2 | 2.8 | 2.4 | 2.4 | 2.9 | 2.8 | 2.6 | 2.4 | 2.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 4.4 | 11.4 | 12.1 | 14.1 | 75.7 | 3.2 | 2.8 | 2.4 | 2.4 | 2.9 | 2.8 | 2.6 | 2.4 | 2.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Advertising | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 161 | 50 | 44 | 29 | 0.4 | 288 | 438 | 420 | 492 | 368 | 435 | 384 | 445 | 405 | 415 | 361 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 36.3 | 33.8 | 27.6 | 24.4 | 2.1 | 30.6 | 30.3 | 31.9 | 32.7 | 30.7 | 30.8 | 31.5 | 32.2 | 29.3 | 29.3 | 30.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 36.3 | 33.8 | 27.6 | 24.4 | 2.1 | 30.6 | 30.3 | 31.9 | 32.7 | 30.7 | 30.8 | 31.5 | 32.2 | 29.3 | 29.3 | 30.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:FoodAndBeverage | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 30 | 11 | 17 | 10 | 3.3 | 55 | 91 | 67 | 82 | 65 | 76 | 54 | 66 | 65 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.9 | 8.0 | 11.0 | 8.9 | 17.5 | 5.9 | 6.3 | 5.1 | 5.5 | 5.5 | 5.4 | 4.4 | 4.8 | 4.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.9 | 8.0 | 11.0 | 8.9 | 17.5 | 5.9 | 6.3 | 5.1 | 5.5 | 5.5 | 5.4 | 4.4 | 4.8 | 4.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 414 | 126 | 134 | 96 | 3.6 | 851 | 1335 | 1215 | 1410 | 1110 | 1326 | 1162 | 1333 | 1333 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 93.1 | 85.5 | 82.6 | 80.6 | 19.0 | 90.5 | 92.3 | 92.3 | 93.6 | 92.5 | 93.9 | 95.2 | 96.4 | 96.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 93.1 | 85.5 | 82.6 | 80.6 | 19.0 | 90.5 | 92.3 | 92.3 | 93.6 | 92.5 | 93.9 | 95.2 | 96.4 | 96.4 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:TransferredAtPointInTime | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 30 | 21 | 28 | 23 | 15 | 89 | 112 | 101 | 95 | 90 | 86 | 59 | 50 | 50 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.9 | 14.5 | 17.4 | 19.4 | 81.0 | 9.5 | 7.7 | 7.7 | 6.4 | 7.5 | 6.1 | 4.8 | 3.6 | 3.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 6.9 | 14.5 | 17.4 | 19.4 | 81.0 | 9.5 | 7.7 | 7.7 | 6.4 | 7.5 | 6.1 | 4.8 | 3.6 | 3.6 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:TransferredOverTime | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 444 | 148 | 162 | 119 | 18 | 941 | 1447 | 1316 | 1506 | 1200 | 1413 | 1221 | 1442 | 1383 | 1416 | 1178 | 1202 | 1283 | 926 | 779 | 763 | 766 | 783 | 688 | 821 | 653 | 712 | 633 | 726 | 622 | 712 | 695 | 762 | 577 |
| 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 |
| 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 | 104.3 | 100.0 | 100.0 | 100.0 | 100.0 | 100.2 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 69 | 11 | 60 | 72 | 3.2 | 280 | 423 | 346 | 344 | 333 |
| Percentage of Revenues | 15.7 | 7.5 | 37.0 | 60.4 | 16.9 | 29.8 | 29.3 | 26.3 | 22.9 | 27.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 15.7 | 7.5 | 37.0 | 60.4 | 16.9 | 29.8 | 29.3 | 26.3 | 22.9 | 27.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments amch:InternationalMarkets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 |
| Value | 374 | 137 | 102 | 47 | 15 | 661 | 1024 | 970 | 1161 | 867 |
| Percentage of Revenues | 84.3 | 92.5 | 63.0 | 39.6 | 83.1 | 70.2 | 70.7 | 73.7 | 77.1 | 72.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 84.3 | 92.5 | 63.0 | 39.6 | 83.1 | 70.2 | 70.7 | 73.7 | 77.1 | 72.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments amch:UsMarkets | 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 |
| Value | 1.1 | 40 |
| Percentage of Revenues | 0.9 | 3.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 0.9 | 3.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:DigitalCinemaImplementationPartnersLLC | 0.0 | 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 | 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 |
| Value | 11329 | 10488 | 10276 | 10876 | 11271 | 11238 | 13675 | 13281 | 13514 | 13473 | 9495 | 9363 | 9531 | 9685 | 9805 | 9910 | 9811 | 9940 | 8641 | 4969 | 4948 | 4931 | 5110 | 4667 | 4739 | 4662 | 4763 | 4612 | 4709 | 4813 | 5046 |
| 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 |
| 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 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 615 | 1182 |
| Percentage of Assets | 6.0 | 8.6 |
| Percentage of Assets | 6.0 | 8.6 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 100.0 | 100.0 |
| 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 | 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 |
| Value | 12733 | 12775 | 13134 | 13211 | 12847 | 12312 | 12461 | 12098 | 12189 | 12169 | 8097 | 8108 | 7561 | 7600 | 7692 | 7485 | 7334 | 7338 | 6631 | 3402 | 3394 | 3383 | 3570 | 3151 | 3216 | 3164 | 3249 | 3102 | 3183 | 3300 | 3537 |
| 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 |
| Percentage of Assets | 112.4 | 121.8 | 127.8 | 121.5 | 114.0 | 109.6 | 91.1 | 91.1 | 90.2 | 90.3 | 85.3 | 86.6 | 79.3 | 78.5 | 78.4 | 75.5 | 74.7 | 73.8 | 76.7 | 68.5 | 68.6 | 68.6 | 69.9 | 67.5 | 67.9 | 67.9 | 68.2 | 67.3 | 67.6 | 68.6 | 70.1 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 394 | 482 |
| Percentage of Liabilities | 3.0 | 3.9 |
| Percentage of Assets | 3.8 | 3.5 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 64.1 | 40.8 |
| 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 | 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 |
| Value | 11329 | 10488 | 10276 | 10876 | 11271 | 11238 | 13675 | 13281 | 13514 | 13473 | 9495 | 9363 | 9531 | 9685 | 9805 | 9910 | 9811 | 9940 | 8641 | 4969 | 4948 | 4931 | 5110 | 4667 | 4739 | 4662 | 4763 | 4612 | 4709 | 4813 | 5046 |
| 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 |
| 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 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 615 | 1182 |
| Percentage of LiabilitiesAndStockholdersEquity | 6.0 | 8.6 |
| Percentage of Assets | 6.0 | 8.6 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 100.0 | 100.0 |
| 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 | 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 | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214 | 1183 | 1325 | 1303 | 1397 | 1254 | 1969 | 2084 | 2112 | 2424 | 2476 | 2600 | 2009 | 1565 | 1552 | 1546 | 1538 | 1513 | 1521 | 1496 | 1512 | 1509 | 1524 | 1511 | 1507 | 766 |
| Percentage of StockholdersEquity | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | -12.4 | -22.0 | -28.1 | -21.8 | -14.0 | -9.6 | 8.9 | 8.9 | 9.8 | 9.7 | 14.7 | 13.4 | 20.7 | 21.5 | 21.5 | 24.5 | 25.2 | 26.2 | 23.3 | 31.5 | 31.4 | 31.4 | 30.1 | 32.4 | 32.1 | 32.1 | 31.8 | 32.7 | 32.4 | 31.4 | 29.9 | 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 | 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 | 2013-12-31 |
| Value | -17.6 | -17.9 | -21.4 | -16.4 | -16.6 | -17.2 | -17.3 | -1.6 | -1.7 | -1.7 | -1.8 | -7.4 | -7.5 | -7.2 | -6.6 | -4.1 | -4.1 | -3.5 | -3.569 | -3.276 | -3.281 | -3.285 | -3.289 | -4.597 | -3.493 | -3.499 | 5.564 | 19 | 20 |
| Percentage of StockholdersEquity | 1.3 | 0.8 | 0.7 | 0.7 | 1.1 | 1.6 | -1.4 | -0.1 | -0.1 | -0.1 | -0.1 | -0.6 | -0.4 | -0.3 | -0.3 | -0.2 | -0.2 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 | -0.2 | -0.2 | 0.4 | 1.3 | 1.4 |
| Percentage of Assets | -0.2 | -0.2 | -0.2 | -0.2 | -0.1 | -0.2 | -0.1 | -0.0 | -0.0 | -0.0 | -0.0 | -0.1 | -0.1 | -0.1 | -0.1 | -0.0 | -0.0 | -0.0 | -0.0 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0.1 | 0.4 | 0.4 |
| Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 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 | 2013-12-31 | 2012-12-31 |
| Value | 8.2 | -12.3 | 38 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26 | 33 | 140 | 125 | 105 | 72 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12 | 24 | 24 | 9.444 |
| Percentage of StockholdersEquity | -0.6 | 0.5 | -1.3 | 2.2 | 4.0 | 11.1 | -2.1 | -8.2 | -2.2 | -1.5 | 0.4 | 2.1 | 1.7 | 6.7 | 5.9 | 4.4 | 2.9 | -0.2 | -0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.1 | 0.2 | 0.3 | 0.8 | 1.6 | 1.6 | 1.2 |
| Percentage of Assets | 0.1 | -0.1 | 0.4 | -0.5 | -0.6 | -1.1 | -0.2 | -0.7 | -0.2 | -0.1 | 0.1 | 0.3 | 0.4 | 1.5 | 1.3 | 1.1 | 0.7 | -0.0 | -0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.0 | 0.1 | 0.1 | 0.3 | 0.5 | 0.5 | 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 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 | 2013-12-31 |
| Value | 25 | 5.6 | 60 | -35.6 | -47.0 | -102.4 | -8.8 | -95.1 | -26.9 | -17.7 | 7.2 | 33 | 39 | 145 | 129 | 107 | 73 | -4.0 | -1.78 | 2.867 | 2.707 | 2.03 | 2.101 | 1.608 | 1.01 | 1.705 | 0.627 | 0.306 | -0.351 |
| Percentage of StockholdersEquity | -1.8 | -0.2 | -2.1 | 1.5 | 3.0 | 9.5 | -0.7 | -8.0 | -2.0 | -1.4 | 0.5 | 2.7 | 2.0 | 7.0 | 6.1 | 4.4 | 3.0 | -0.2 | -0.1 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.0 | 0.0 | -0.0 |
| Percentage of Assets | 0.2 | 0.1 | 0.6 | -0.3 | -0.4 | -0.9 | -0.1 | -0.7 | -0.2 | -0.1 | 0.1 | 0.4 | 0.4 | 1.5 | 1.3 | 1.1 | 0.7 | -0.0 | -0.0 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | -0.0 |
| Percentage of Assets us-gaap:AccumulatedTranslationAdjustment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 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 |
| Value | 2012 | 1016 | 487 | 608 | 679 | 551 | 673 | 448 | 590 | 551 | 781 | 686 | 840 | 738 | 872 | 622 | 622 | 891 | 683 | 195 | 255 | 286 | 414 | 347 | 462 | 387 | 509 | 369 | 474 | 601 | 843 |
| 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 |
| Percentage of Assets | 17.8 | 9.7 | 4.7 | 5.6 | 6.0 | 4.9 | 4.9 | 3.4 | 4.4 | 4.1 | 8.2 | 7.3 | 8.8 | 7.6 | 8.9 | 6.3 | 6.3 | 9.0 | 7.9 | 3.9 | 5.2 | 5.8 | 8.1 | 7.5 | 9.8 | 8.3 | 10.7 | 8.0 | 10.1 | 12.5 | 16.7 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 267 | 339 |
| Percentage of AssetsCurrent | 54.9 | 50.4 |
| Percentage of Assets | 2.6 | 2.5 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 43.5 | 28.7 |
| 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 | 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 | 2012-08-31 |
| Value | 1811 | 813 | 308 | 417 | 498 | 299 | 265 | 100 | 190 | 184 | 313 | 333 | 316 | 300 | 310 | 260 | 127 | 313 | 207 | 46 | 93 | 107 | 211 | 97 | 179 | 144 | 218 | 155 | 235 | 353 | 546 | 130 | 136 | 106 | 133 | 100 |
| 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 |
| Percentage of Assets | 16.0 | 7.8 | 3.0 | 3.8 | 4.4 | 2.7 | 1.9 | 0.8 | 1.4 | 1.4 | 3.3 | 3.6 | 3.3 | 3.1 | 3.2 | 2.6 | 1.3 | 3.1 | 2.4 | 0.9 | 1.9 | 2.2 | 4.1 | 2.1 | 3.8 | 3.1 | 4.6 | 3.4 | 5.0 | 7.3 | 10.8 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2015-12-31 |
| Value | 1839 | 842 | 321 | 428 | 508 | 309 | 275 | 110 | 201 | 195 | 324 | 344 | 327 | 312 | 318 | 291 | 159 | 336 | 230 | 211 |
| 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 |
| Percentage of Assets | 16.2 | 8.0 | 3.1 | 3.9 | 4.5 | 2.8 | 2.0 | 0.8 | 1.5 | 1.4 | 3.4 | 3.7 | 3.4 | 3.2 | 3.2 | 2.9 | 1.6 | 3.4 | 2.7 | 4.1 |
| 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 | 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 |
| Value | 88 | 86 | 91 | 97 | 70 | 126 | 254 | 157 | 228 | 193 | 259 | 155 | 179 | 167 | 271 | 128 | 153 | 144 | 213 | 57 | 67 | 85 | 105 | 56 | 81 | 48 | 99 | 42 | 63 | 53 | 106 |
| Percentage of ReceivablesNetCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 0.8 | 0.8 | 0.9 | 0.9 | 0.6 | 1.1 | 1.9 | 1.2 | 1.7 | 1.4 | 2.7 | 1.7 | 1.9 | 1.7 | 2.8 | 1.3 | 1.6 | 1.5 | 2.5 | 1.2 | 1.4 | 1.7 | 2.1 | 1.2 | 1.7 | 1.0 | 2.1 | 0.9 | 1.3 | 1.1 | 2.1 |
| 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 | 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 |
| Value | 84 | 87 | 74 | 82 | 100 | 115 | 143 | 180 | 160 | 162 | 197 | 187 | 203 | 204 | 202 | 226 | 223 | 211 | 262 | 91 | 94 | 93 | 97 | 84 | 93 | 86 | 84 | 80 | 82 | 83 | 80 |
| Percentage of OtherAssetsCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 0.7 | 0.8 | 0.7 | 0.8 | 0.9 | 1.0 | 1.0 | 1.4 | 1.2 | 1.2 | 2.1 | 2.0 | 2.1 | 2.1 | 2.1 | 2.3 | 2.3 | 2.1 | 3.0 | 1.8 | 1.9 | 1.9 | 1.9 | 1.8 | 2.0 | 1.9 | 1.8 | 1.8 | 1.8 | 1.7 | 1.6 |
| 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 | 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 | 2014-12-31 | 2013-12-31 |
| Value | 9316 | 9472 | 9789 | 10267 | 10591 | 10686 | 13002 | 12832 | 12924 | 12921 | 8714 | 8676 | 8690 | 8947 | 8933 | 9288 | 9189 | 9049 | 7958 | 7958 | 7958 | 7958 | 4695 | 4253 | 4203 |
| Percentage of NoncurrentAssets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 82.2 | 90.3 | 95.3 | 94.4 | 94.0 | 95.1 | 95.1 | 96.6 | 95.6 | 95.9 | 91.8 | 92.7 | 91.2 | 92.4 | 91.1 | 93.7 | 93.7 | 91.0 | 92.1 | 160.1 | 160.8 | 161.4 | 91.9 | 89.3 | 83.3 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 2703 | 2744 | 2894 | 3177 | 3059 | 2987 | 3963 |
| Percentage of NoncurrentAssets | 29.0 | 29.0 | 29.6 | 30.9 | 28.9 | 28.0 | 30.5 |
| Percentage of Assets | 23.9 | 26.2 | 28.2 | 29.2 | 27.1 | 26.6 | 29.0 |
| Percentage of Assets us-gaap:OperatingSegments amch:InternationalMarkets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 |
| Value | 6613 | 6727 | 6895 | 7090 | 7532 | 7698 | 9039 |
| Percentage of NoncurrentAssets | 71.0 | 71.0 | 70.4 | 69.1 | 71.1 | 72.0 | 69.5 |
| Percentage of Assets | 58.4 | 64.1 | 67.1 | 65.2 | 66.8 | 68.5 | 66.1 |
| Percentage of Assets us-gaap:OperatingSegments amch:UsMarkets | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 347 | 843 |
| Percentage of AssetsNoncurrent | 100.0 | 100.0 |
| Percentage of Assets | 3.4 | 6.2 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 56.5 | 71.3 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 4492 | 4388 |
| Percentage of PropertyPlantAndEquipmentGross | 100.0 | 100.0 |
| Percentage of Assets | 43.7 | 32.1 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 2343 | 2216 |
| Percentage of PropertyPlantAndEquipmentGross | 52.2 | 50.5 |
| Percentage of Assets | 22.8 | 16.2 |
| Percentage of Assets amch:FurnitureFixturesAndEquipment | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 222 | 230 |
| Percentage of PropertyPlantAndEquipmentGross | 4.9 | 5.3 |
| Percentage of Assets | 2.2 | 1.7 |
| Percentage of Assets us-gaap:BuildingAndBuildingImprovements | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 92 | 106 |
| Percentage of PropertyPlantAndEquipmentGross | 2.1 | 2.4 |
| Percentage of Assets | 0.9 | 0.8 |
| Percentage of Assets us-gaap:Land | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 1833 | 1834 |
| Percentage of PropertyPlantAndEquipmentGross | 40.8 | 41.8 |
| Percentage of Assets | 17.8 | 13.4 |
| Percentage of Assets us-gaap:LeaseholdImprovements | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2019-12-31 |
| Value | 2417 | 2330 | 2232 | 1812 |
| Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 21.3 | 22.2 | 21.7 | 13.3 |
| 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 |
| Value | 2260 | 2332 | 2417 | 2520 | 2649 | 2581 | 2613 | 2600 | 3039 | 3028 | 3028 | 3091 | 3116 | 3244 | 3254 | 3162 | 3035 | 1537 | 1447 | 1409 | 1401 | 1313 | 1278 | 1266 | 1247 | 1214 | 1207 | 1192 | 1179 |
| 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 |
| Percentage of Assets | 22.0 | 21.4 | 21.4 | 22.4 | 19.4 | 19.4 | 19.3 | 19.3 | 32.0 | 32.3 | 31.8 | 31.9 | 31.8 | 32.7 | 33.2 | 31.8 | 35.1 | 30.9 | 29.3 | 28.6 | 27.4 | 28.1 | 27.0 | 27.2 | 26.2 | 26.3 | 25.6 | 24.8 | 23.4 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2017-01-31 | 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 | 2472 | 2491 | 2547 | 2874 | 2988 | 2938 | 4789 | 4693 | 4763 | 4787 | 4788 | 4820 | 4830 | 4944 | 4931 | 4889 | 4832 | 4823 | 4823 | 3932 | 2410 | 2410 | 2410 | 2406 | 2289 | 2289 | 2289 | 2289 | 2289 | 2289 | 2289 | 2289 | 2249 |
| Percentage of Goodwill | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 21.8 | 23.7 | 24.8 | 26.4 | 26.5 | 26.1 | 35.0 | 35.3 | 35.2 | 35.5 | 50.4 | 51.5 | 50.7 | 51.0 | 50.3 | 49.3 | 49.2 | 48.5 | 0.0 | 45.5 | 48.5 | 48.7 | 48.9 | 47.1 | 49.1 | 48.3 | 49.1 | 48.1 | 49.6 | 48.6 | 47.6 | 45.4 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2547 | 2874 | 2938 | 2938 |
| Percentage of Goodwill | 100.0 | 100.0 | 98.3 | 100.0 |
| Percentage of Assets | 24.8 | 26.4 | 26.1 | 26.1 |
| Percentage of Assets us-gaap:FairValueInputsLevel3 us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2547 | 2874 | 2938 | 2938 |
| Percentage of Goodwill | 100.0 | 100.0 | 98.3 | 100.0 |
| Percentage of Assets | 24.8 | 26.4 | 26.1 | 26.1 |
| Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 405 | 156 | 1744 | 1744 |
| Percentage of Goodwill | 15.9 | 5.5 | 58.4 | 59.4 |
| Percentage of Assets | 3.9 | 1.4 | 15.5 | 15.5 |
| Percentage of Assets us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 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 |
| Value | 1796 | 1796 | 1796 | 1796 | 1947 | 1947 | 3072 |
| Percentage of Goodwill | 72.7 | 72.1 | 70.5 | 62.5 | 65.2 | 66.3 | 64.2 |
| Percentage of Assets | 15.9 | 17.1 | 17.5 | 16.5 | 17.3 | 17.3 | 22.5 |
| Percentage of Assets amch:DomesticTheatres | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 |
| Value | 675 | 694 | 750 | 1077 | 1040 | 990 | 1716 |
| Percentage of Goodwill | 27.3 | 27.9 | 29.5 | 37.5 | 34.8 | 33.7 | 35.8 |
| Percentage of Assets | 6.0 | 6.6 | 7.3 | 9.9 | 9.2 | 8.8 | 12.6 |
| Percentage of Assets amch:InternationalTheatres | 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 | 2015-12-31 | 2014-12-31 |
| Value | 1796 | 3100 | 3072 | 3072 | 3072 | 3072 | 3072 | 3072 | 3072 | 3072 | 3047 | 3045 | 3044 | 2406 | 2289 |
| Percentage of Goodwill | 70.5 | 64.7 | 65.5 | 64.5 | 64.2 | 64.2 | 63.7 | 63.6 | 62.1 | 62.3 | 62.3 | 63.0 | 77.4 | 100.0 | 100.0 |
| Percentage of Assets | 17.5 | 22.7 | 23.1 | 22.7 | 22.8 | 32.4 | 32.8 | 32.2 | 31.7 | 31.3 | 30.7 | 31.0 | 35.2 | 47.1 | 48.1 |
| Percentage of Assets country:US | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 750 | 1716 | 1621 | 1690 | 1715 | 1716 | 1748 | 1758 | 1871 | 1859 | 1842 | 1787 | 888 |
| Percentage of Goodwill | 29.5 | 35.8 | 34.5 | 35.5 | 35.8 | 35.8 | 36.3 | 36.4 | 37.9 | 37.7 | 37.7 | 37.0 | 22.6 |
| Percentage of Assets | 7.3 | 12.6 | 12.2 | 12.5 | 12.7 | 18.1 | 18.7 | 18.4 | 19.3 | 19.0 | 18.6 | 18.2 | 10.3 |
| Percentage of Assets us-gaap:NonUs | 0.0 | 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 | 2015-12-31 | 2014-12-31 | 2013-12-31 |
| Value | 152 | 165 | 166 | 169 | 155 | 112 | 104 | 104 |
| Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 1.5 | 1.2 | 1.8 | 1.7 | 1.8 | 2.2 | 2.2 | 2.1 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 44 | 43 | 50 | 50 |
| Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill | 28.9 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 0.4 | 0.4 | 0.4 | 0.4 |
| Percentage of Assets us-gaap:FairValueInputsLevel3 us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 44 | 43 | 50 | 50 |
| Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill | 28.9 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 0.4 | 0.4 | 0.4 | 0.4 |
| Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2.3 | 4.6 | 8.3 | 8.3 |
| Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill | 1.5 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.1 | 0.1 |
| Percentage of Assets us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 156 | 158 | 163 | 164 | 174 | 175 | 195 | 193 | 197 | 199 | 352 | 359 | 365 | 378 | 380 | 387 | 389 | 362 | 365 | 231 | 233 | 235 | 237 | 219 | 221 | 223 | 225 | 227 | 229 | 232 | 234 |
| Percentage of IntangibleAssetsNetExcludingGoodwill | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 1.4 | 1.5 | 1.6 | 1.5 | 1.5 | 1.6 | 1.4 | 1.5 | 1.5 | 1.5 | 3.7 | 3.8 | 3.8 | 3.9 | 3.9 | 3.9 | 4.0 | 3.6 | 4.2 | 4.7 | 4.7 | 4.8 | 4.6 | 4.7 | 4.7 | 4.8 | 4.7 | 4.9 | 4.9 | 4.8 | 4.6 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 6400000.0 | 8000000.0 | 8000000.0 |
| Percentage of FiniteLivedIntangibleAssetsNet | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 |
| Percentage of Assets us-gaap:FairValueMeasurementsNonrecurring | 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 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 |
| Value | 40 | 24 | 19 | 20 | 14 | 13 | 14 | 16 | 20 | 20 | 174 | 69 | 126 | 181 | 206 |
| Percentage of DeferredTaxAssetsLiabilitiesNet | 100.0 | 100.0 | 100.0 | 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 | 0.2 | 0.1 | 0.2 | 0.1 | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 | 1.8 | 0.8 | 2.5 | 3.8 | 4.1 |
| 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 |
| Value | 4308 | 4348 | 4451 | 4475 | 4555 | 4602 | 4796 | 4794 | 4798 | 4809 |
| Percentage of OperatingLeaseRightOfUseAsset | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 38.0 | 41.5 | 43.3 | 41.2 | 40.4 | 41.0 | 35.1 | 36.1 | 35.5 | 35.7 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 69 | 56 | 124 | 124 | 123 |
| Percentage of OperatingLeaseRightOfUseAsset | 1.6 | 1.3 | 2.7 | 2.7 | 2.6 |
| Percentage of Assets | 0.7 | 0.5 | 1.1 | 1.1 | 0.9 |
| Percentage of Assets us-gaap:FairValueInputsLevel3 us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 69 | 56 | 124 | 124 | 123 |
| Percentage of OperatingLeaseRightOfUseAsset | 1.6 | 1.3 | 2.7 | 2.7 | 2.6 |
| Percentage of Assets | 0.7 | 0.5 | 1.1 | 1.1 | 0.9 |
| Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 261 | 273 | 304 | 419 | 455 | 450 | 503 | 537 | 520 | 493 | 505 | 438 | 438 | 505 | 475 | 544 | 509 | 595 | 533 | 518 | 508 | 483 | 523 | 433 | 436 | 419 | 417 | 415 | 410 | 400 | 402 |
| 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 |
| Percentage of Assets | 2.3 | 2.6 | 3.0 | 3.9 | 4.0 | 4.0 | 3.7 | 4.1 | 3.9 | 3.7 | 5.3 | 4.7 | 4.6 | 5.2 | 4.9 | 5.5 | 5.2 | 6.0 | 6.2 | 10.4 | 10.3 | 9.8 | 10.2 | 9.3 | 9.2 | 9.0 | 8.8 | 9.0 | 8.7 | 8.3 | 8.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2019-12-31 |
| Value | 12 | 10 | 10 | 10 | 11 |
| Percentage of EquitySecuritiesFvNi | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Percentage of Assets us-gaap:FairValueMeasurementsRecurring | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 235 | 264 | 298 | 376 | 436 | 337 | 543 | 361 | 423 | 382 | 452 | 395 | 535 | 454 | 569 | 469 | 477 | 510 | 501 | 261 | 298 | 240 | 313 | 212 | 268 | 210 | 262 | 181 | 258 | 223 | 268 |
| 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 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 2.1 | 2.5 | 2.9 | 3.5 | 3.9 | 3.0 | 4.0 | 2.7 | 3.1 | 2.8 | 4.8 | 4.2 | 5.6 | 4.7 | 5.8 | 4.7 | 4.9 | 5.1 | 5.8 | 5.3 | 6.0 | 4.9 | 6.1 | 4.5 | 5.7 | 4.5 | 5.5 | 3.9 | 5.5 | 4.7 | 5.3 |
| 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 | 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 |
| Value | 1558 | 1584 | 1578 | 1588 | 1711 | 1612 | 1933 | 1647 | 1713 | 1692 | 1328 | 1158 | 1243 | 1222 | 1409 | 1180 | 1146 | 1238 | 1189 | 595 | 620 | 583 | 712 | 558 | 616 | 554 | 636 | 503 | 583 | 553 | 657 |
| 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 |
| Percentage of Assets | 13.8 | 15.1 | 15.4 | 14.6 | 15.2 | 14.3 | 14.1 | 12.4 | 12.7 | 12.6 | 14.0 | 12.4 | 13.0 | 12.6 | 14.4 | 11.9 | 11.7 | 12.5 | 13.8 | 12.0 | 12.5 | 11.8 | 13.9 | 12.0 | 13.0 | 11.9 | 13.4 | 10.9 | 12.4 | 11.5 | 13.0 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 181 | 222 |
| Percentage of LiabilitiesCurrent | 11.5 | 11.5 |
| Percentage of Assets | 1.8 | 1.6 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 29.4 | 18.8 |
| 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 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 |
| Value | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 21 | 21 | 15 | 15 | 15 | 15 | 10 | 15 |
| 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 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.1 | 0.2 | 0.2 | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 | 0.3 |
| 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 |
| Value | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 21 | 21 | 15 | 15 |
| 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 |
| Percentage of Assets | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.1 | 0.2 | 0.2 | 0.1 | 0.2 |
| Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 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 | 604 | 591 | 583 | 511 | 581 | 581 | 585 | 568 | 570 | 570 |
| Percentage of OperatingLeaseLiabilityCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 5.3 | 5.6 | 5.7 | 4.7 | 5.2 | 5.2 | 4.3 | 4.3 | 4.2 | 4.2 |
| 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 | 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 |
| Value | 286 | 291 | 257 | 268 | 257 | 263 | 324 | 338 | 317 | 342 | 378 | 387 | 312 | 348 | 351 | 337 | 289 | 330 | 328 | 151 | 131 | 141 | 158 | 160 | 153 | 136 | 136 | 148 | 141 | 135 | 170 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 2.5 | 2.8 | 2.5 | 2.5 | 2.3 | 2.3 | 2.4 | 2.5 | 2.4 | 2.5 | 4.0 | 4.1 | 3.3 | 3.6 | 3.6 | 3.4 | 3.0 | 3.3 | 3.8 | 3.1 | 2.7 | 2.9 | 3.1 | 3.4 | 3.2 | 2.9 | 2.9 | 3.2 | 3.0 | 2.8 | 3.4 |
| 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 |
| Value | 87 | 114 | 157 | 146 | 118 | 23 | 14 | 19 |
| Percentage of OtherLiabilitiesCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.8 | 0.8 | 1.7 | 1.5 | 1.4 | 0.5 | 0.3 | 0.4 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 213 | 260 |
| Percentage of LiabilitiesNoncurrent | 100.0 | 100.0 |
| Percentage of Assets | 2.1 | 1.9 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 34.7 | 22.0 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2019-12-31 | 2018-12-31 |
| Value | 5214 | 5411 | 5448 | 4910 | 4867 |
| Percentage of LongTermDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 46.0 | 52.7 | 50.1 | 35.9 | 51.3 |
| 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 | 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 |
| Value | 5480 | 5439 | 5695 | 5803 | 5498 | 5020 | 4733 | 4710 | 4713 | 4737 | 4707 | 4840 | 4202 | 4244 | 4220 | 4277 | 4249 | 4180 | 3745 | 1843 | 1824 | 1851 | 1924 | 1746 | 1748 | 1771 | 1775 | 1780 | 1783 | 1932 | 2069 |
| 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 |
| Percentage of Assets | 48.4 | 51.9 | 55.4 | 53.4 | 48.8 | 44.7 | 34.6 | 35.5 | 34.9 | 35.2 | 49.6 | 51.7 | 44.1 | 43.8 | 43.0 | 43.2 | 43.3 | 42.1 | 43.3 | 37.1 | 36.9 | 37.5 | 37.7 | 37.4 | 36.9 | 38.0 | 37.3 | 38.6 | 37.9 | 40.1 | 41.0 |
| 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 | 2015-06-30 | 2015-03-31 |
| Value | 5480 | 5439 | 5695 | 5803 | 5498 | 5020 | 4733 | 4710 | 4713 | 4737 | 4707 | 4833 | 1748 | 1771 |
| 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 | 99.9 | 100.0 | 100.0 |
| Percentage of Assets | 48.4 | 51.9 | 55.4 | 53.4 | 48.8 | 44.7 | 34.6 | 35.5 | 34.9 | 35.2 | 49.6 | 51.6 | 36.9 | 38.0 |
| Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure | 0.0 | 0.0 | 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 | 2015-12-31 | 2014-12-31 | 2013-12-31 |
| Value | 8.3 | 11 | 6.7 | 9.5 | 7.707 | 31 | 13 | 7.841 |
| Percentage of DeferredFinanceCostsNoncurrentNet | 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 | 0.1 | 0.6 | 0.3 | 0.2 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 |
| Value | 28 | 34 | 40 | 43 | 43 | 47 | 46 | 49 | 51 | 45 | 41 | 44 | 44 | 48 | 49 | 47 | 46 | 26 | 20 |
| Percentage of DeferredIncomeTaxLiabilitiesNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 0.3 | 0.3 | 0.4 | 0.4 | 0.4 | 0.4 | 0.3 | 0.4 | 0.4 | 0.3 | 0.4 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.3 | 0.2 |
| 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 |
| Value | 64 | 59 | 54 | 62 | 44 | 42 | 48 | 30 |
| Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.6 | 0.4 | 0.6 | 0.6 | 0.5 | 0.8 | 1.0 | 0.6 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 22 | 26 | 34 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.3 | 0.3 |
| Period End | 2020-08-28 |
| Value | 34 |
| Percentage of MinorityInterest | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations amch:ForumCinemasOu | 0.0 |
| Period End | 2021-03-31 | 2020-09-30 |
| Value | 22 | 34 |
| Percentage of MinorityInterest | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.3 |
| Percentage of Assets amch:ForumCinemasOu | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 26 |
| Percentage of MinorityInterest | 100.0 |
| Percentage of Assets | 0.3 |
| Percentage of Assets amch:LithuaniaAndEstonia us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations amch:ForumCinemasOu | 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 | 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 |
| Value | 188 | 207 | 241 | 240 | 220 | 212 | 195 | 190 | 192 | 188 | 963 | 980 | 963 | 937 | 903 | 847 | 746 | 726 | 706 | 513 | 492 | 484 | 462 | 438 | 437 | 419 | 419 | 394 | 387 | 378 | 370 |
| 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 |
| Percentage of Assets | 1.7 | 2.0 | 2.3 | 2.2 | 2.0 | 1.9 | 1.4 | 1.4 | 1.4 | 1.4 | 10.1 | 10.5 | 10.1 | 9.7 | 9.2 | 8.6 | 7.6 | 7.3 | 8.2 | 10.3 | 10.0 | 9.8 | 9.1 | 9.4 | 9.2 | 9.0 | 8.8 | 8.6 | 8.2 | 7.9 | 7.4 |
| 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 |
| Value | 4888 | 4908 | 4957 | 4909 | 4744 | 4784 | 4913 | 4857 | 4852 | 4826 |
| Percentage of OperatingLeaseLiabilityNoncurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 43.2 | 46.8 | 48.2 | 45.1 | 42.1 | 42.6 | 35.9 | 36.6 | 35.9 | 35.8 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 941 | 895 | 971 | 922 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 8.3 | 8.5 | 9.5 | 8.5 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 816 | 792 | 862 | 830 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 7.2 | 7.6 | 8.4 | 7.6 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 770 | 756 | 785 | 763 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 6.8 | 7.2 | 7.6 | 7.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 704 | 691 | 752 | 728 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 6.2 | 6.6 | 7.3 | 6.7 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 3768 | 3719 | 4371 | 4228 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 33.3 | 35.5 | 42.5 | 38.9 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 5493 | 5500 | 5541 | 5420 |
| Percentage of OperatingLeaseLiability | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 48.5 | 52.4 | 53.9 | 49.8 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 8574 | 8653 | 8788 | 8658 |
| Percentage of LesseeOperatingLeaseLiabilityPaymentsDue | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 75.7 | 82.5 | 85.5 | 79.6 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 3081 | 3153 | 3246 | 3237 |
| Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 27.2 | 30.1 | 31.6 | 29.8 |
| 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 | 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 | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214 | 1183 | 1325 | 1303 | 1397 | 1254 | 1969 | 2084 | 2112 | 2424 | 2476 | 2600 | 2009 | 1565 | 1552 | 1546 | 1538 | 1513 | 1521 | 1496 | 1512 | 1509 | 1524 | 1511 | 1507 | 766 |
| Percentage of StockholdersEquity | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | -12.4 | -22.0 | -28.1 | -21.8 | -14.0 | -9.6 | 8.9 | 8.9 | 9.8 | 9.7 | 14.7 | 13.4 | 20.7 | 21.5 | 21.5 | 24.5 | 25.2 | 26.2 | 23.3 | 31.5 | 31.4 | 31.4 | 30.1 | 32.4 | 32.1 | 32.1 | 31.8 | 32.7 | 32.4 | 31.4 | 29.9 | 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 | 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 | 2013-12-31 |
| Value | -17.6 | -17.9 | -21.4 | -16.4 | -16.6 | -17.2 | -17.3 | -1.6 | -1.7 | -1.7 | -1.8 | -7.4 | -7.5 | -7.2 | -6.6 | -4.1 | -4.1 | -3.5 | -3.569 | -3.276 | -3.281 | -3.285 | -3.289 | -4.597 | -3.493 | -3.499 | 5.564 | 19 | 20 |
| Percentage of StockholdersEquity | 1.3 | 0.8 | 0.7 | 0.7 | 1.1 | 1.6 | -1.4 | -0.1 | -0.1 | -0.1 | -0.1 | -0.6 | -0.4 | -0.3 | -0.3 | -0.2 | -0.2 | -0.1 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.3 | -0.2 | -0.2 | 0.4 | 1.3 | 1.4 |
| Percentage of Assets | -0.2 | -0.2 | -0.2 | -0.2 | -0.1 | -0.2 | -0.1 | -0.0 | -0.0 | -0.0 | -0.0 | -0.1 | -0.1 | -0.1 | -0.1 | -0.0 | -0.0 | -0.0 | -0.0 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0.1 | 0.4 | 0.4 |
| Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 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 | 2013-12-31 | 2012-12-31 |
| Value | 8.2 | -12.3 | 38 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26 | 33 | 140 | 125 | 105 | 72 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12 | 24 | 24 | 9.444 |
| Percentage of StockholdersEquity | -0.6 | 0.5 | -1.3 | 2.2 | 4.0 | 11.1 | -2.1 | -8.2 | -2.2 | -1.5 | 0.4 | 2.1 | 1.7 | 6.7 | 5.9 | 4.4 | 2.9 | -0.2 | -0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.1 | 0.2 | 0.3 | 0.8 | 1.6 | 1.6 | 1.2 |
| Percentage of Assets | 0.1 | -0.1 | 0.4 | -0.5 | -0.6 | -1.1 | -0.2 | -0.7 | -0.2 | -0.1 | 0.1 | 0.3 | 0.4 | 1.5 | 1.3 | 1.1 | 0.7 | -0.0 | -0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.0 | 0.1 | 0.1 | 0.3 | 0.5 | 0.5 | 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 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 | 2013-12-31 |
| Value | 25 | 5.6 | 60 | -35.6 | -47.0 | -102.4 | -8.8 | -95.1 | -26.9 | -17.7 | 7.2 | 33 | 39 | 145 | 129 | 107 | 73 | -4.0 | -1.78 | 2.867 | 2.707 | 2.03 | 2.101 | 1.608 | 1.01 | 1.705 | 0.627 | 0.306 | -0.351 |
| Percentage of StockholdersEquity | -1.8 | -0.2 | -2.1 | 1.5 | 3.0 | 9.5 | -0.7 | -8.0 | -2.0 | -1.4 | 0.5 | 2.7 | 2.0 | 7.0 | 6.1 | 4.4 | 3.0 | -0.2 | -0.1 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.0 | 0.0 | -0.0 |
| Percentage of Assets | 0.2 | 0.1 | 0.6 | -0.3 | -0.4 | -0.9 | -0.1 | -0.7 | -0.2 | -0.1 | 0.1 | 0.4 | 0.4 | 1.5 | 1.3 | 1.1 | 0.7 | -0.0 | -0.0 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | -0.0 |
| Percentage of Assets us-gaap:AccumulatedTranslationAdjustment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 |
| Value | -1404.7 | -2287.0 | -2858.2 | -2335.4 | -1575.4 | -1074.0 | 1214 | 1397 | 2112 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | -12.4 | -21.8 | -27.8 | -21.5 | -14.0 | -9.6 | 8.9 | 14.7 | 21.5 |
| Period End | 2020-12-31 | 2019-12-31 |
| Value | 220 | 699 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -7.7 | 57.6 |
| Percentage of Assets | 2.1 | 5.1 |
| Percentage of Assets us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvestees | 35.9 | 59.2 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 0.6 | 0.5 | 0.5 | 0.5 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.0 | -0.0 | -0.0 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2017-12-31 |
| Value | 5.1 | 4.5 | 1.8 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.4 | -0.2 | -0.1 | -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 |
| Percentage of Assets us-gaap:CommonClassA 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 |
| 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 | 2017-12-31 |
| Value | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.8 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -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 |
| Percentage of Assets us-gaap:CommonClassB us-gaap:CommonStock | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2017-12-31 |
| Value | 8.2 | -12.3 | 38 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 125 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -0.6 | 0.5 | -1.4 | 2.2 | 4.0 | 11.1 | -2.1 | 0.0 | 0.0 | 0.0 | 0.4 | 5.9 |
| Percentage of Assets | 0.1 | -0.1 | 0.4 | -0.5 | -0.6 | -1.1 | -0.2 | -0.7 | -0.2 | -0.1 | 0.1 | 1.3 |
| 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 |
| 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 | 2017-12-31 |
| Value | 4847 | 3657 | 2465 | 2125 | 2007 | 2003 | 2001 | 2008 | 2006 | 2001 | 1998 | 2241 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -345.1 | -159.9 | -86.3 | -91.0 | -127.4 | -186.6 | 164.9 | 0.0 | 0.0 | 0.0 | 143.0 | 106.1 |
| Percentage of Assets | 42.8 | 34.9 | 24.0 | 19.5 | 17.8 | 17.8 | 14.6 | 15.1 | 14.8 | 14.9 | 21.0 | 22.9 |
| 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 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 22 | 26 | 34 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | -1.0 | -0.9 | -1.5 |
| Percentage of Assets | 0.2 | 0.3 | 0.3 |
| Percentage of Assets us-gaap:NoncontrollingInterest | 0.0 | 0.0 | 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 | 2017-12-31 |
| Value | -1404.7 | -2309.4 | -2885.1 | -2370.1 | -1575.4 | -1074.0 | 1214 | 1183 | 1325 | 1303 | 1397 | 2112 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 100.0 | 101.0 | 100.9 | 101.5 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 |
| Percentage of Assets | -12.4 | -22.0 | -28.1 | -21.8 | -14.0 | -9.6 | 8.9 | 8.9 | 9.8 | 9.7 | 14.7 | 21.5 |
| Percentage of Assets us-gaap:Parent | 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 | 2021-06-30 | 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 | 2017-12-31 |
| Value | -6265.4 | -5902.3 | -5335.3 | -4387.8 | -3463.7 | -2902.6 | -706.2 | -673.5 | -597.7 | -623.4 | -550.9 | -207.9 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 446.0 | 258.1 | 186.7 | 187.9 | 219.9 | 270.3 | -58.2 | 0.0 | 0.0 | 0.0 | -39.4 | -9.8 |
| Percentage of Assets | -55.3 | -56.3 | -51.9 | -40.3 | -30.7 | -25.8 | -5.2 | -5.1 | -4.4 | -4.6 | -5.8 | -2.1 |
| 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 |
| 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 | 2018-12-31 | 2017-12-31 |
| Value | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -56.4 | -48.2 |
| Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 2.5 | 2.0 | 2.4 | 3.6 | 5.3 | -4.6 | 0.0 | 0.0 | 0.0 | -4.0 | -2.3 |
| Percentage of Assets | -0.5 | -0.5 | -0.5 | -0.5 | -0.5 | -0.4 | -0.4 | -0.4 | -0.4 | -0.6 | -0.5 |
| Percentage of Assets us-gaap:TreasuryStockCommon | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 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 |
| Value | 5100000.0 | 4500000.0 | 1800000.0 | 600000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 600000.0 | 600000.0 | 342000.0 | 215000.0 | 215000.0 | 215000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 | 214000.0 |
| 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 | 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 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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:CommonClassA | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 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 |
| Value | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 500000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 800000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 | 758000.0 |
| Percentage of CommonStockValue | 27.8 | 83.3 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 160.0 | 160.0 | 160.0 | 160.0 | 133.3 | 133.3 | 221.6 | 352.6 | 352.6 | 352.6 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 | 354.2 |
| 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 |
| Percentage of Assets us-gaap:CommonClassB | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 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 |
| Value | 4847 | 3657 | 2465 | 2125 | 2007 | 2003 | 2001 | 2008 | 2006 | 2001 | 1998 | 1994 | 2247 | 2242 | 2241 | 2240 | 2240 | 2237 | 1627 | 1187 | 1185 | 1184 | 1183 | 1182 | 1179 | 1178 | 1172 | 1167 | 1168 | 1167 | 1161 |
| Percentage of AdditionalPaidInCapitalCommonStock | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 42.8 | 34.9 | 24.0 | 19.5 | 17.8 | 17.8 | 14.6 | 15.1 | 14.8 | 14.9 | 21.0 | 21.3 | 23.6 | 23.2 | 22.9 | 22.6 | 22.8 | 22.5 | 18.8 | 23.9 | 24.0 | 24.0 | 23.2 | 25.3 | 24.9 | 25.3 | 24.6 | 25.3 | 24.8 | 24.3 | 23.0 |
| 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 | 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 |
| Value | -6265.4 | -5902.3 | -5335.3 | -4387.8 | -3463.7 | -2902.6 | -706.2 | -673.5 | -597.7 | -623.4 | -550.9 | -710.6 | -255.5 | -251.7 | -207.9 | 94 | 163 | 366 | 384 | 376 | 365 | 360 | 352 | 330 | 337 | 313 | 327 | 316 | 329 | 317 | 321 |
| 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 |
| Percentage of Assets | -55.3 | -56.3 | -51.9 | -40.3 | -30.7 | -25.8 | -5.2 | -5.1 | -4.4 | -4.6 | -5.8 | -7.6 | -2.7 | -2.6 | -2.1 | 1.0 | 1.7 | 3.7 | 4.4 | 7.6 | 7.4 | 7.3 | 6.9 | 7.1 | 7.1 | 6.7 | 6.9 | 6.9 | 7.0 | 6.6 | 6.4 |
| 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 | 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 | 8.2 | -12.3 | 38 | -52.0 | -63.6 | -119.6 | -26.1 | -96.7 | -28.6 | -19.4 | 5.5 | 26 | 33 | 140 | 125 | 105 | 72 | -4.4 | -2.551 | 2.07 | 1.596 | 0.922 | 2.804 | 1.146 | 3.108 | 4.228 | 12 | 24 | 26 | 26 | 24 | 6.784 | 17 | 13 | 9.444 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.1 | -0.1 | 0.4 | -0.5 | -0.6 | -1.1 | -0.2 | -0.7 | -0.2 | -0.1 | 0.1 | 0.3 | 0.4 | 1.5 | 1.3 | 1.1 | 0.7 | -0.0 | -0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.0 | 0.1 | 0.1 | 0.3 | 0.5 | 0.6 | 0.5 | 0.5 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 22 | 26 | 34 |
| Percentage of MinorityInterest | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.3 | 0.3 |
| Period End | 2020-08-28 |
| Value | 34 |
| Percentage of MinorityInterest | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations amch:ForumCinemasOu | 0.0 |
| Period End | 2021-03-31 | 2020-09-30 |
| Value | 22 | 34 |
| Percentage of MinorityInterest | 100.0 | 100.0 |
| Percentage of Assets | 0.2 | 0.3 |
| Percentage of Assets amch:ForumCinemasOu | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 26 |
| Percentage of MinorityInterest | 100.0 |
| Percentage of Assets | 0.3 |
| Percentage of Assets amch:LithuaniaAndEstonia us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations amch:ForumCinemasOu | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 989 | 581 | 2.8 | 0.0 | 0.0 | -0.9 | 617 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 100.0 | 100.0 | 100.0 | 0.0 | 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 | 2021-06-30 |
| Value | 230 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 23.3 |
| Percentage of Assets | 0.0 |
| Percentage of Assets amch:MudrickCapitalManagementLp | 0.0 |
| Period End | 2021-06-30 |
| Value | 0.1 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 0.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets amch:MudrickCapitalManagementLp us-gaap:CommonClassA us-gaap:CommonStock | 0.0 |
| Period End | 2021-06-30 |
| Value | 230 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 23.3 |
| Percentage of Assets | 0.0 |
| Percentage of Assets amch:MudrickCapitalManagementLp us-gaap:AdditionalPaidInCapital | 0.0 |
| Period End | 2021-06-30 |
| Value | 230 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 23.3 |
| Percentage of Assets | 0.0 |
| Percentage of Assets amch:MudrickCapitalManagementLp us-gaap:Parent | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2017-03-31 |
| Value | 0.5 | 1.8 | 0.2 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 0.1 | 0.3 | 0.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:CommonClassA us-gaap:CommonStock | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 951 | 579 | 2.8 | -0.9 | 617 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 96.2 | 99.7 | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 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 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 |
| Value | 989 | 581 | 2.8 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 100.0 | 100.0 | 100.0 |
| Percentage of Assets | 0.0 | 0.0 | 0.0 |
| Percentage of Assets us-gaap:Parent | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 |
| Value | -19.3 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | -2.0 |
| Percentage of Assets | 0.0 |
| Percentage of Assets us-gaap:RetainedEarnings | 0.0 |
| Period End | 2021-06-30 |
| Value | 56 |
| Percentage of StockIssuedDuringPeriodValueNewIssues | 5.7 |
| Percentage of Assets | 0.0 |
| Percentage of Assets us-gaap:TreasuryStockCommon | 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 | 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 | -233.8 | -312.9 | -357.9 | -355.7 | -231.9 | -184.0 | 368 | 56 | 152 | 1.4 | 224 | 1.7 | 131 | 165 | 329 | 119 | -62.7 | 172 | 220 | 77 | 111 | 22 | 258 | 16 | 171 | 21 | 178 | 12 | 107 | -1.575 | 152 | 71 | 97 | 35 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -52.6 | -211.0 | -220.2 | -297.7 | -1227.0 | -19.5 | 25.5 | 4.3 | 10.1 | 0.1 | 15.9 | 0.1 | 9.5 | 12.0 | 23.3 | 10.1 | -5.2 | 13.5 | 23.8 | 9.9 | 14.5 | 3.0 | 32.9 | 2.4 | 20.9 | 3.3 | 25.1 | 1.9 | 14.8 | -0.3 | 21.4 | 10.2 | 12.8 | 6.2 |
| 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 | 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 | 13 | -16.0 | 0.2 | -23.3 | -44.1 | -87.4 | -167.7 | -127.1 | -122.8 | -98.5 | -202.9 | 67 | -66.7 | -114.8 | -149.9 | 66 | -138.5 | -743.5 | -1106.3 | -120.302 | -76.373 | -51.625 | -292.314 | -72.826 | -72.882 | -71.378 | -88.2 | -68.772 | -56.488 | -58.231 | -88.506 | -71.878 | -70.099 | -38.301 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.0 | -10.8 | 0.1 | -19.5 | -233.3 | -9.3 | -11.6 | -9.7 | -8.2 | -8.2 | -14.4 | 5.5 | -4.8 | -8.3 | -10.6 | 5.7 | -11.5 | -58.0 | -119.5 | -15.4 | -10.0 | -6.7 | -37.3 | -10.6 | -8.9 | -10.9 | -12.4 | -10.8 | -7.8 | -9.4 | -12.4 | -10.3 | -9.2 | -6.6 |
| 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 | 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 | 1212 | 854 | 247 | 296 | 473 | 312 | -40.0 | -18.4 | -20.6 | -33.9 | -39.5 | -37.4 | -55.5 | -62.4 | -128.7 | -60.2 | 6.9 | 674 | 1046 | -3.979 | -49.239 | -74.582 | 147 | -24.603 | -63.837 | -23.645 | -27.799 | -23.378 | -169.325 | -133.362 | 351 | -4.962 | 2.435 | -24.228 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 272.6 | 576.3 | 152.5 | 248.2 | 2505.3 | 33.2 | -2.8 | -1.4 | -1.4 | -2.8 | -2.8 | -3.1 | -4.0 | -4.5 | -9.1 | -5.1 | 0.6 | 52.6 | 112.9 | -0.5 | -6.4 | -9.7 | 18.8 | -3.6 | -7.8 | -3.6 | -3.9 | -3.7 | -23.3 | -21.4 | 49.3 | -0.7 | 0.3 | -4.2 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 997 | 520 | -107.4 | -79.6 | 198 | 34 | 164 | -90.6 | 6.0 | -128.8 | -20.3 | 16 | 14 | -5.8 | 26 | 131 | -176.5 | 106 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 224.3 | 351.1 | -66.1 | -66.6 | 1050.8 | 3.6 | 11.4 | -6.9 | 0.4 | -10.7 | -1.4 | 1.4 | 1.1 | -0.4 | 1.9 | 11.2 | -14.7 | 8.3 |
| 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 |
| Value | 3.4 | 12 | 2.6 | 3.2 | 4.3 | 4.1 | 4.0 | 4.0 | 3.4 | 4.4 |
| Percentage of AmortizationOfFinancingCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 |
| Value | 0.0 |
| Percentage of AmortizationOfFinancingCosts | 0.0 |
| Period End | 2020-12-31 |
| Value | 0.4 |
| Percentage of AmortizationOfFinancingCosts | 15.4 |
| Period End | 2021-03-31 |
| Value | 1.0 |
| Percentage of AmortizationOfFinancingCosts | 8.3 |
| 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 | 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 | -6.1 | -6.2 | -1.2 | -0.2 | -5.8 | 71 | -40.7 | -1.9 | 4.8 | 4.1 | -2.9 | -1.5 | -3.5 | 1.5 | 295 | -19.6 | -109.5 | -8.8 | -11.545 | 16 | 12 | 16 | 33 | -10.953 | 25 | 3.525 | 12 | 4.225 | 18 | -2.89 | -275.028 | 2.8 | 2.83 | 2.8 |
| Percentage of DeferredIncomeTaxExpenseBenefit | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 105 | 114 | 132 | 123 | 119 | 122 | 112 | 112 | 112 | 113 | 139 | 130 | 137 | 130 | 144 | 135 | 133 | 125 | 82 | 63 | 62 | 60 | 59 | 58 | 57 | 57 | 55 | 54 | 51 | 54 | 50 | 48 | 50 | 48 |
| 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 |
| 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 |
| Value | 2.7 | 0.9 | 1.0 | 0.7 | 0.7 | 0.8 | 0.6 | 0.5 | 1.7 | 0.6 |
| Percentage of DepreciationDepletionAndAmortization | 2.6 | 0.8 | 0.8 | 0.6 | 0.6 | 0.7 | 0.5 | 0.4 | 1.5 | 0.5 |
| 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 | 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 | -56.0 | -11.9 | -55.2 | -66.2 | 114 | -169.8 | 206 | -65.5 | 41 | -76.7 | 105 | -149.0 | 65 | -107.1 | 151 | -18.3 | -28.1 | -69.9 | 138 | -70.081 | 34 | -81.48 | 111 | -75.598 | 64 | -58.998 | 77 | -68.514 | 28 | -51.71 | 88 | -62.828 | 43 | -4.897 |
| Percentage of IncreaseDecreaseInAccountsPayable | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | -2.2 | 11 | 5.6 | -19.3 | -6.0 | -23.5 | 4.3 | 1.0 | 7.7 | -5.5 | 1.5 | 1.0 | 8.1 | -4.5 | 8.1 | 13 | -4.8 | -0.4 | -1.21 | -0.526 | -1.419 | -1.059 | -4.294 | -0.402 | -0.436 | 3.718 | -2.044 | -4.408 | 16 | -8.016 | 0.285 | -12.741 | 9.741 | 2.823 |
| 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 |
| 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 | 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 | -233.8 | -312.9 | -357.9 | -355.7 | -231.9 | -184.0 | 368 | 56 | 152 | 1.4 | 224 | 1.7 | 131 | 165 | 329 | 119 | -62.7 | 172 | 220 | 77 | 111 | 22 | 258 | 16 | 171 | 21 | 178 | 12 | 107 | -1.575 | 152 | 71 | 97 | 35 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -52.6 | -211.0 | -220.2 | -297.7 | -1227.0 | -19.5 | 25.5 | 4.3 | 10.1 | 0.1 | 15.9 | 0.1 | 9.5 | 12.0 | 23.3 | 10.1 | -5.2 | 13.5 | 23.8 | 9.9 | 14.5 | 3.0 | 32.9 | 2.4 | 20.9 | 3.3 | 25.1 | 1.9 | 14.8 | -0.3 | 21.4 | 10.2 | 12.8 | 6.2 |
| 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 | 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 | -343.6 | -566.9 | -945.8 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49 | -130.2 | 170 | -100.4 | 22 | 17 | -276.4 | -42.7 | -176.5 | 8.4 | 29 | 30 | 24 | 28 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.3 | -382.3 | -582.0 | -758.0 | -2969.3 | -231.2 | -0.9 | -4.2 | 3.3 | -10.8 | 12.1 | -8.2 | 1.6 | 1.3 | -19.5 | -3.6 | -14.7 | 0.7 | 3.1 | 3.9 | 3.1 | 3.7 |
| Period End | 2021-03-31 |
| Value | -0.3 |
| Percentage of NetIncomeLoss | 0.1 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -0.2 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest | 0.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -566.9 | -905.8 | -561.2 | -2176.3 | -54.8 | 49 | -130.2 |
| Percentage of NetIncomeLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -382.3 | -758.0 | -2969.3 | -231.2 | -4.2 | 3.3 | -10.8 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | -566.9 | -905.8 | -561.2 | -2176.3 | -54.8 | 49 | -130.2 | -100.4 | 22 | 17 | -42.7 | -176.5 | 8.4 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -382.3 | -758.0 | -2969.3 | -231.2 | -4.2 | 3.3 | -10.8 | -8.2 | 1.6 | 1.3 | -3.6 | -14.7 | 0.7 |
| 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 | 2021-06-30 | 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 |
| Value | -344.0 | -567.2 | -946.1 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 49 | -130.2 | 170 | -100.4 | 22 | 17 | -276.4 | -42.7 | -176.5 | 8.4 |
| 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 | 100.0 | 100.0 | 100.0 | 100.0 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -77.4 | -382.5 | -582.2 | -758.0 | -2969.3 | -231.2 | -0.9 | -4.2 | 3.3 | -10.8 | 12.1 | -8.2 | 1.6 | 1.3 | -19.5 | -3.6 | -14.7 | 0.7 |
| Period End | 2020-09-30 | 2019-09-30 |
| Value | -30.6 | 22 |
| Percentage of ProfitLoss | 3.4 | -40.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | -25.6 | 1.7 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax amch:DigitalCinemaImplementationPartnersLLC | 0.0 | 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 | 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 | 8.4 | 5.4 | 15 | 3.1 | 3.7 | 2.7 | -7.1 | 2.1 | 5.4 | 4.0 | 4.0 | 4.1 | 4.0 | 2.8 | 1.8 | -0.1 | 3.9 | 0.1 | 0.346 | 1.705 | 1.717 | 1.087 | 1.103 | 2.199 | 1.439 | 5.739 | 5.221 | -1.596 | 1.311 | 6.357 |
| Percentage of ShareBasedCompensation | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 13 | -16.0 | 0.2 | -23.3 | -44.1 | -87.4 | -167.7 | -127.1 | -122.8 | -98.5 | -202.9 | 67 | -66.7 | -114.8 | -149.9 | 66 | -138.5 | -743.5 | -1106.3 | -120.302 | -76.373 | -51.625 | -292.314 | -72.826 | -72.882 | -71.378 | -88.2 | -68.772 | -56.488 | -58.231 | -88.506 | -71.878 | -70.099 | -38.301 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 3.0 | -10.8 | 0.1 | -19.5 | -233.3 | -9.3 | -11.6 | -9.7 | -8.2 | -8.2 | -14.4 | 5.5 | -4.8 | -8.3 | -10.6 | 5.7 | -11.5 | -58.0 | -119.5 | -15.4 | -10.0 | -6.7 | -37.3 | -10.6 | -8.9 | -10.9 | -12.4 | -10.8 | -7.8 | -9.4 | -12.4 | -10.3 | -9.2 | -6.6 |
| 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 | 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 | 17 | 11 | 17 | 29 | 35 | 91 | 169 | 118 | 115 | 114 | 201 | 133 | 133 | 107 | 159 | 149 | 156 | 161 | 165 | 116 | 82 | 57 | 117 | 71 | 74 | 69 | 87 | 67 | 59 | 55 | 85 | 70 | 65 | 39 |
| Percentage of PaymentsToAcquireProductiveAssets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 4.1 | 5.3 | 8.0 | 11 | 10 | 34 | 44 | 34 | 31 | 39 |
| Percentage of PaymentsToAcquireProductiveAssets | 22.9 | 44.5 | 44.9 | 37.5 | 28.9 | 37.9 | 26.1 | 28.7 | 26.9 | 34.2 |
| 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 |
| Value | 13 | 6.6 | 9.8 | 18 | 24 | 56 | 125 | 84 | 84 | 75 |
| Percentage of PaymentsToAcquireProductiveAssets | 77.1 | 55.5 | 55.1 | 62.5 | 71.1 | 62.1 | 73.9 | 71.3 | 73.1 | 65.8 |
| 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 | 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 | 1212 | 854 | 247 | 296 | 473 | 312 | -40.0 | -18.4 | -20.6 | -33.9 | -39.5 | -37.4 | -55.5 | -62.4 | -128.7 | -60.2 | 6.9 | 674 | 1046 | -3.979 | -49.239 | -74.582 | 147 | -24.603 | -63.837 | -23.645 | -27.799 | -23.378 | -169.325 | -133.362 | 351 | -4.962 | 2.435 | -24.228 |
| 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 |
| Percentage of RevenueFromContractWithCustomerExcludingAssessedTax | 272.6 | 576.3 | 152.5 | 248.2 | 2505.3 | 33.2 | -2.8 | -1.4 | -1.4 | -2.8 | -2.8 | -3.1 | -4.0 | -4.5 | -9.1 | -5.1 | 0.6 | 52.6 | 112.9 | -0.5 | -6.4 | -9.7 | 18.8 | -3.6 | -7.8 | -3.6 | -3.9 | -3.7 | -23.3 | -21.4 | 49.3 | -0.7 | 0.3 | -4.2 |
| 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 |
| Value | 2.2 | 0.0 | 0.0 | 4.3 | 20 | 20 | 20 | 21 | 20 | 186 | 25 | 25 | 25 | 78 | 52 | 26 | 20 | 19 | 19 | 19 | 19 | 19 | 19 | 19 | 19 | 19 |
| Percentage of PaymentsOfDividends | 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-02-15 |
| Value | 10.75 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 100.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:OdeonCinemasGroupLimited amch:FourHundredMillionTermLoanFacility us-gaap:SubsequentEvent | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-10-15 | 2020-09-30 | 2020-07-31 | 2020-06-30 | 2020-04-24 | 2020-04-23 | 2020-04-15 | 2019-12-31 |
| Value | 10.5 | 10.5 | 10.5 | 10.5 | 10.5 | 10.5 | 0.105 | 0.105 | 0.105 | 0.105 | 0.105 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:FirstLienNotesDue2025 | 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 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 2.6 | 0.026 | 0.026 | 0.026 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:OdeonRevolvingCreditFacilityDue2022Rate26 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 2.5785 | 0.0317 | 0.0317 | 0.0317 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:OdeonRevolvingCreditFacilityDue2022Rate317 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-07-31 |
| Value | 10.0 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SecondLienNotesDue2026 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 3.0855 | 3.195 | 3.23 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSecuredCreditFacilityTermLoanDue2026 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 10.5 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:FirstLienNotesDue2026 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-01-31 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-06-05 |
| Value | 5.75 | 5.75 | 5.75 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.05875 | 0.05875 | 0.05875 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.0575 | 0.0575 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotes5.75PercentDue2025 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-12-31 | 2016-11-08 |
| Value | 5.875 | 5.875 | 5.875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 | 0.05875 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotes5.875PercentDue2026 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2017-03-17 | 2016-12-31 |
| Value | 6.125 | 6.125 | 6.125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 | 0.06125 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotes6.125PercentDue2027 | 0.0 | 0.0 | 0.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-17 | 2017-01-31 | 2016-12-31 | 2016-11-08 |
| Value | 6.375 | 6.375 | 6.375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 | 0.06375 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 | 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 LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotes6.375PercentDue2024 | 0.0 | 0.0 | 0.0 | 0.0 | 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 | 2020-07-31 |
| Value | 0.0575 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotesDue5.75Percent2025 | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.05875 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotesDue5.875Percent2026 | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.06125 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotesDue6.125Percent2027 | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.06375 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotesDue6.375Percent2024 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-07-31 | 2020-03-31 | 2019-12-31 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-09-14 |
| Value | 2.95 | 2.95 | 2.95 | 0.0295 | 0.0295 | 0.0295 | 0.0295 | 0.0295 | 0.0295 | 0.0295 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorUnsecuredConvertibleNotesDue2024 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.105 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:New10.500SeniorSecuredNotesDue2026 us-gaap:SubsequentEvent | 0.0 |
| Period End | 2020-07-13 | 2020-06-03 |
| Value | 0.0295 | 0.06375 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations amch:SeniorSubordinatedNotesDue6.375Percent2024 us-gaap:SubsequentEvent | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 2.74 | 2.76 | 0.0287 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Maximum us-gaap:RevolvingCreditFacility | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 2.65 | 2.65 | 0.0236 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 | 0.0 | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Minimum us-gaap:RevolvingCreditFacility | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 12.0 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Maximum amch:SecondLienSubordinatedSecuredNotesDue2026 | 0.0 |
| Period End | 2020-09-30 |
| Value | 10.0 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Minimum amch:SecondLienSubordinatedSecuredNotesDue2026 | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.12 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Maximum amch:SecondLienSubordinatedSecuredNotesDue2026 us-gaap:SubsequentEvent | 0.0 |
| Period End | 2020-07-31 |
| Value | 0.1 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Minimum amch:SecondLienSubordinatedSecuredNotesDue2026 us-gaap:SubsequentEvent | 0.0 |
| Period End | 2020-12-31 |
| Value | 17.0 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Maximum amch:DebtAgreementWithMudrickCapitalManagementLp | 0.0 |
| Period End | 2020-12-31 |
| Value | 15.0 |
| Percentage of DebtInstrumentInterestRateStatedPercentage | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations | 0.0 |
| Percentage of LongTermDebtAndCapitalLeaseObligations srt:Minimum amch:DebtAgreementWithMudrickCapitalManagementLp | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 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 | 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 | 0.1 | 1.2 | -3.2 | 0.218 | 0.073 | -0.115 | -0.045 | 0.389 | -0.329 | -0.159 | 0.209 | -0.856 | -0.021 | -0.0075 | 0 | 0.0075 | 0.39 | -0.004 | 0.016 | -0.037 | 0.39 | -0.046 | 0 | 0 | 0.39 | -2.76 | -0.018 | 0.392 | -0.255 |
| 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 | 0.0 | 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 | 2020-12-31 | 2019-12-31 | 2018-12-31 | 2017-12-31 | 2016-12-31 | 2015-12-31 | 2014-12-31 | 2013-12-31 |
| Value | 1328 | 1542 | 455 | 500 | 795 | 489 | 453 | 423 |
| Percentage of DeferredTaxLiabilities | 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 |
| Value | 1288 | 1566 | 442 | 479 | 864 | 615 | 635 | 630 |
| Percentage of DeferredTaxAssetsNet | 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 | 2012-08-30 |
| Value | 33 | 31 | 22 | 15 | 12 | 30 | 30 | 27 | 24 | 24 |
| Percentage of UnrecognizedTaxBenefits | 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 | 2012-08-30 |
| Value | 764 | 312 | 323 | 338 | 112 | 0.509 | 0.79 | 0.8 | 248 | 232 |
| Percentage of DeferredTaxAssetsValuationAllowance | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 |
| Value | 200000.0 | 100000.0 | -100000.0 |
| Percentage of AccruedDividendEquivalentAdjustment | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 200000.0 | 100000.0 |
| Percentage of AccruedDividendEquivalentAdjustment | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 |
| Value | 200000.0 | 100000.0 | -100000.0 |
| Percentage of AccruedDividendEquivalentAdjustment | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 |
| Value | 100000.0 |
| Percentage of AccruedDividendEquivalentAjustment | 100.0 |
| Period End | 2021-03-31 |
| Value | 100000.0 |
| Percentage of AccruedDividendEquivalentAjustment | 100.0 |
| Period End | 2021-03-31 |
| Value | 100000.0 |
| Percentage of AccruedDividendEquivalentAjustment | 100.0 |
| 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 | 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 | 150 | 294 | -1670.9 | 334 | -340.3 | 3.1 | 269 | 156 | 237 | 108 | 264 | 142 | 244 | 277 | 288 | 147 | 135 | 251 | 181 | 144 | 129 | 146 |
| Percentage of AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 94 | -398.2 | 75 | -98.7 | 6.9 | 302 | -40.2 | 35 | 30 |
| Percentage of AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization | 21.8 | 32.0 | 23.8 | 22.5 | 29.0 | 222.6 | 112.3 | -25.7 | 14.9 | 28.4 |
| 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 |
| Value | 118 | 200 | -1272.7 | 259 | -241.6 | -3.8 | 971 | -116.3 | 202 | 77 |
| Percentage of AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization | 78.2 | 68.0 | 76.2 | 77.5 | 71.0 | -122.6 | 361.0 | -74.3 | 85.1 | 71.6 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 483 | 195 | 0.0 | 1859 |
| Percentage of AssetImpairmentChargesIncludingNonControllingInterest | 100.0 | 100.0 | 0.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 |
| Value | 700000.0 | -800000.0 | 1100000.0 | -1400000.0 | 600000.0 | -100000.0 | -8800000.0 | 900000.0 | 2000000.0 | 900000.0 | 3600000.0 | 2100000.0 | -400000.0 | 2000000.0 | 1600000.0 | 800000.0 | 1000000.0 |
| Percentage of AttributableEarningsBeforeInterestTaxesDepreciationAndAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 700000.0 | -800000.0 | 1100000.0 | -1400000.0 | 600000.0 | -100000.0 | 1200000.0 | 900000.0 | 2000000.0 | 900000.0 |
| Percentage of AttributableEarningsBeforeInterestTaxesDepreciationAndAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | -13.6 | 100.0 | 100.0 | 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 |
| Value | 0.0 | 0.0 | 0.0 | 0.0 | -1.4 | 0.0 | 0.0 |
| Percentage of BusinessCombinationConsiderationSettlementValueOfUnitsReturnedUnderUnitAdjustmentAgreement | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 388 |
| Percentage of CashBurn | 100.0 |
| Period End | 2020-07-31 |
| Value | 180 |
| Percentage of CashSavingsDueToInterestPayments | 100.0 |
| Period End | 2020-07-31 |
| Value | 120 |
| Percentage of CashSavingsDueToInterestPayments | 66.7 |
| Period End | 2020-07-31 |
| Value | 180 |
| Percentage of CashSavingsDueToInterestPayments | 100.0 |
| Period End | 2020-07-31 |
| Value | 180 |
| Percentage of CashSavingsDueToInterestPayments | 100.0 |
| Period End | 2020-07-31 |
| Value | 120 |
| Percentage of CashSavingsDueToInterestPayments | 66.7 |
| Period End | 2020-07-31 |
| Value | 120 |
| Percentage of CashSavingsDueToInterestPayments | 66.7 |
| Period End | 2021-06-30 |
| Value | 21 |
| Percentage of ComprehensiveIncomeLossNetOfTaxIncludingInvestmentAttributableToNoncontrollingInterest | 100.0 |
| Period End | 2021-06-30 |
| Value | 21 |
| Percentage of ComprehensiveIncomeLossNetOfTaxIncludingInvestmentAttributableToNoncontrollingInterest | 100.0 |
| Period End | 2021-06-30 |
| Value | 21 |
| Percentage of ComprehensiveIncomeLossNetOfTaxIncludingInvestmentAttributableToNoncontrollingInterest | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 900000.0 | -3400000.0 | 2900000.0 |
| Percentage of ContractWithCustomerLiabilityForeignCurrencyTranslationAdjustment | 100.0 | 100.0 | 100.0 |
| 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 | -4500000.0 | -4400000.0 | -4400000.0 | -4300000.0 | -4100000.0 | -4100000.0 | -4100000.0 | -3900000.0 | -3900000.0 | -3800000.0 | -3700000.0 | -3700000.0 |
| Percentage of ContractWithCustomerLiabilityRevenueReclassed | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -5600000.0 | -900000.0 | -8000000.0 | -3600000.0 | -1000000.0 | -21200000.0 |
| Percentage of ContractWithCustomerLiabilityRevenueReclassed | 124.4 | 20.5 | 181.8 | 83.7 | 24.4 | 517.1 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -14100000.0 | -7200000.0 | -6500000.0 | -23700000.0 | 1200000.0 | -89500000.0 |
| Percentage of ContractWithCustomerLiabilityRevenueReclassed | 313.3 | 163.6 | 147.7 | 551.2 | -29.3 | 2182.9 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -7400000.0 | -3900000.0 | -4700000.0 | -2200000.0 | -1300000.0 | -23800000.0 |
| Percentage of ContractWithCustomerLiabilityRevenueReclassed | 164.4 | 88.6 | 106.8 | 51.2 | 31.7 | 580.5 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 18 | 15 | 17 |
| Percentage of ContractsWithCustomersCashReceivedInAdvance | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | -9200000.0 |
| Percentage of ContractsWithCustomersDeferredRevenueNegativeCommonUnitAdjustment | 0.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 2.9 |
| Percentage of ConvertibleDebtCarryingValueAdjustments | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 0.2 | 36 |
| Percentage of DebtFeesPaidToThirdParties | 100.0 | 100.0 |
| Period End | 2020-09-30 |
| Value | 87.0 |
| Percentage of DebtInstrumentExchangeOfDebtPercentage | 100.0 |
| Period End | 2020-07-31 |
| Value | 83.61 |
| Percentage of DebtInstrumentExchangePricePercentageOfPrincipalAmountExchanged | 100.0 |
| Period End | 2020-07-31 |
| Value | 90.65 |
| Percentage of DebtInstrumentExchangePricePercentageOfPrincipalAmountExchanged | 108.4 |
| Period End | 2020-07-31 |
| Value | 72.48 |
| Percentage of DebtInstrumentExchangePricePercentageOfPrincipalAmountExchanged | 86.7 |
| Period End | 2020-07-31 |
| Value | 99.2 |
| Percentage of DebtInstrumentExchangePricePercentageOfPrincipalAmountExchanged | 118.6 |
| Period End | 2020-07-31 |
| Value | 501 |
| Percentage of DebtInstrumentExchangePriceReductionOfPrincipalAmountExchanged | 100.0 |
| Period End | 2020-07-31 |
| Value | 539 |
| Percentage of DebtInstrumentExchangePriceReductionOfPrincipalAmountExchanged | 107.5 |
| Period End | 2020-07-31 |
| Value | 344 |
| Percentage of DebtInstrumentExchangePriceReductionOfPrincipalAmountExchanged | 68.6 |
| Period End | 2020-07-31 |
| Value | 632 |
| Percentage of DebtInstrumentExchangePriceReductionOfPrincipalAmountExchanged | 126.0 |
| Period End | 2021-02-15 |
| Value | 11.25 |
| Percentage of DebtInstrumentInterestRatePaymentInCash | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 17.0 |
| Percentage of DebtInstrumentPaidInKindInterestRatePercentage | 0.0 | 100.0 |
| Period End | 2020-07-31 |
| Value | 12.0 |
| Percentage of DebtInstrumentPaidInKindInterestRatePercentage | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 12.0 |
| Percentage of DebtInstrumentPaidInKindInterestRatePercentage | 0.0 | 70.6 |
| Period End | 2020-09-30 |
| Value | -2400000.0 |
| Percentage of DecreaseInAccumulatedEarningsDueToDerivativeAssetValuationAllowanceAdjustment | 100.0 |
| Period End | 2020-09-30 |
| Value | -2400000.0 |
| Percentage of DecreaseInAccumulatedEarningsDueToDerivativeAssetValuationAllowanceAdjustment | 100.0 |
| Period End | 2020-09-30 |
| Value | -2400000.0 |
| Percentage of DecreaseInAccumulatedEarningsDueToDerivativeAssetValuationAllowanceAdjustment | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -4800000.0 | -4600000.0 |
| Percentage of DeferredFinanceLeaseLiabilityChanges | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -1400000.0 | -25900000.0 |
| Percentage of DeferredVariableLeaseLiabilityChanges | 100.0 | 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 | -39.2 | 5.9 | -6.4 | 20 | -17.2 | -8.5 | -7.1 | 15 |
| Percentage of DerivativeAssetFairValueAdjustment | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-03-31 |
| Value | -13.7 | 14 | -6.4 | -20.1 | -15.1 |
| Percentage of DerivativeAssetFairValueAdjustment | 0.0 | 244.1 | 100.0 | -100.0 | -100.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 0.0 | 26 |
| Percentage of DerivativeAssetValuationImmaterialCorrectionExpense | 0.0 | 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 |
| Value | -0.5 | 0.0 | 89 | 0.0 | -0.5 | -8.6 | 5.7 | -33.9 | 13 |
| Percentage of DerivativeGainLossOnDerivativeNotEliminatedFromEarningsPerShareCalculation | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 |
| Value | -178.8 | 89 | 0.0 | -0.5 | 38 | 5.7 | -33.9 | 13 | -120.5 | 54 |
| Percentage of DerivativeLiabilityFairValueAdjustment | 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 | 2019-03-31 |
| Value | 4.7 | 84 | 19 | 0.5 | -13.3 |
| Percentage of DerivativeLiabilityFairValueAdjustment | -2.6 | 93.7 | 0.0 | -100.0 | -100.0 |
| Period End | 2020-08-28 |
| Value | 1000000.0 |
| Percentage of DisposalGroupIncludingDiscontinuedOperationTransactionCost | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-08-28 |
| Value | 2600000.0 | 100000.0 | 1400000.0 |
| Percentage of DisposalGroupIncludingDiscontinuedOperationTransactionCost | 0.0 | 0.0 | 140.0 |
| Period End | 2021-05-31 |
| Value | 300000.0 |
| Percentage of DisposalGroupIncludingDiscontinuedOperationTransactionCost | 0.0 |
| Period End | 2021-03-31 |
| Value | 49.0 |
| Percentage of DisposalGroupNoncontrollingInterestOwnershipPercentageByNoncontrollingOwners | 100.0 |
| 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 |
| Value | -0.3 | -1.2 | -4.4 | -8.7 | -12.2 | -2.1 | 6.0 | 7.4 | 9.8 | 6.0 |
| Percentage of EquityInEarningsLossNonConsolidatedEntitiesExcludingInternationalTheatreJointVentures | 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 | 0 |
| Percentage of EquityMethodInvestmentDistributionReductionBelowRecordedInvestment | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 3700000.0 | -2000000.0 | -3900000.0 | 5300000.0 |
| Percentage of EstimatedCreditIncomeLossesContingentLeaseGuarantees | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2020-06-30 |
| Value | 9200000.0 | 3900000.0 |
| Percentage of EstimatedCreditIncomeLossesContingentLeaseGuarantees | 248.6 | -100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -3700000.0 | 2000000.0 |
| Percentage of EstimatedCreditIncomeLossesContingentLeaseGuarantees | -100.0 | -100.0 |
| 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 | 2018-06-30 | 2018-03-31 |
| Value | 9.4 | 9.9 | 9.9 | 10 | 10 | 9.9 | 10.0 | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Percentage of ExhibitorServiceAgreement | 100.0 | 100.0 | 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 | 2021-06-30 |
| Value | 22 |
| Percentage of GainLossFromLiquidationOfSubsidiary | 100.0 |
| Period End | 2021-06-30 |
| Value | 0.9 |
| Percentage of GainLossFromLiquidationOfSubsidiary | 3.9 |
| Period End | 2021-06-30 |
| Value | 22 |
| Percentage of GainLossFromLiquidationOfSubsidiary | 96.1 |
| Period End | 2021-06-30 |
| Value | 0.9 |
| Percentage of GainLossFromLiquidationOfSubsidiary | 3.9 |
| Period End | 2021-03-31 |
| Value | 12 |
| Percentage of GovernmentalAssistanceDueToInfrequentItems | 100.0 |
| Period End | 2021-06-30 | 2020-06-30 |
| Value | 42 | 4.4 |
| Percentage of GovernmentalAssistanceDueToInfrequentItemsInInternationalMarkets | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-03-31 |
| Value | 2342 | 1859 |
| Percentage of ImpairmentLossesOfLongLivedAssetsFairValueDisclosures | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2019-09-30 |
| Value | -1900000.0 | 100000.0 |
| Percentage of IncomeLossFromEquityMethodInvestmentsInternationalTheatreJointVentures | 100.0 | 100.0 |
| Period End | 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 | -2400000.0 | -1600000.0 | -1900000.0 | -200000.0 | -800000.0 | 100000.0 | 400000.0 | 500000.0 |
| Percentage of IncomeLossFromEquityMethodInvestmentsInternationalTheatreJointVentures | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 |
| Value | 0.0 | 1.0 | 3.0 | 36 | 2.8 |
| Percentage of IncreaseDecreaseInExpenseDueToFinancingFees | 0.0 | 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 |
| Value | 8.3 | 7.8 | 8.3 | 8.3 | 8.2 | 8.0 | 8.0 |
| Percentage of InterestExpenseNotEliminatedFromNetLossBecauseEffectWouldBeAntidilutive | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 |
| Value | 23 |
| Percentage of InterestPaidOnExchangeOffers | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 |
| Value | 13 | 4.4 |
| Percentage of InternationalGovernmentAssistanceDueToInfrequentItems | 100.0 | 100.0 |
| 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 | 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 | 7.4 | 3.7 | 11 | 7.0 | 8.8 | 16 | 17 | 24 | 29 | 35 | 27 | 27 | 30 | 42 | 56 | 33 | 17 | 25 | 47 | 29 | 68 | -20.309 | -40.122 | -19.507 | -12.726 | -10.991 | -14.33 | -24.693 | -9.201 | -11.294 | -4.131 | -7.159 |
| Percentage of LandlordContributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 4.3 | 6.7 | 21 | 1.0 | 1.8 | 0.2 | 4.3 | 4.7 | 3.2 | 3.3 | 4.2 | 18 | 4.3 | 4.7 | 5.8 | 5.6 | 11 | 40 | 32 | 4.961 | 5.548 | 4.604 | 0.808 | 0.751 | 0.261 | 1.578 | 0.149 | 0.078 | 0.572 | 0.362 | 0.931 | 0.299 | 0.706 | 0.947 |
| Percentage of MergerAcquisitionTransactionCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2017-12-31 | 2017-09-30 |
| Value | 0 | -500000.0 | -600000.0 | 400000.0 | -200000.0 | -1100000.0 | -400000.0 | 300000.0 | 800000.0 | -200000.0 |
| Percentage of MiscellaneousExpense | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2017-12-31 | 2017-09-30 |
| Value | -200000.0 | -200000.0 | 800000.0 | 200000.0 | 100000.0 | 400000.0 | 300000.0 | 400000.0 | 700000.0 | 0 | 100000.0 | -200000.0 | 200000.0 |
| Percentage of NetPeriodicBenefitCostCredit | 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 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 5.8 | 1.4 | -0.3 | -0.4 | 4.5 | 0.3 | -0.1 | 1.4 | 0.0 | 0.0 | 0.0 | -6.3 | 0.0 | 0.0 | 0.0 | 235 |
| Percentage of NoncashInvestmentValueOfAssetsAcquired | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 |
| Period End | 2021-03-31 |
| Value | -3800000.0 |
| Percentage of NoncontrollingInterestIncludedIncreaseFromSubsidiaryEquityIssuance | 100.0 |
| 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 | 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 | -52.6 | -146.2 | 16 | -225.8 | -95.7 | -122.0 | -90.3 | -75.8 | -50.7 | -90.8 | 83 | -67.4 | -70.1 | -87.5 | -56.3 | -56.0 | -266.5 | -56.2 | -20.094 | -15.003 | -15.252 | -12.87 | -10.36 | -14.281 | -26.9 | -21.985 | -19.033 | -16.428 | -16.893 |
| Percentage of NonoperatingIncomeExpenseIncludingIncomeLossFromEquityMethodInvestments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | -300000.0 | 400000.0 | -400000.0 | 1300000.0 |
| Percentage of OperatingExpensesIncomeRelatedParty | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 6.6 | 150 | 18 |
| Percentage of OperatingLeaseCommitmentsNotYetCommenced | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 7.4 | 3.7 | 11 | 7.0 | 8.8 | 16 | 17 | 24 | 29 | 35 |
| Percentage of OperatingLeaseLandlordContributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | -11700000.0 | -7500000.0 | -3800000.0 | 2300000.0 |
| Percentage of OperatingLeaseNonCashExpensesBenefits | 100.0 | 100.0 | 100.0 | 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 | -3.2 | -0.2 | -3.8 | 2.3 | 6.2 | 6.1 | 5.8 | 7.6 |
| Percentage of OperatingLeaseNonCashPayments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2016-09-30 | 2016-06-30 |
| Value | -0.3 | -4.8 | -96.6 | 138 | -1.9 | 26 | -17.9 | -1.5 | -23.8 | 29 | -165.9 | 54 | 2.5 | 1.2 | 0.5 | -0.6 | 1.0 | -2.2 | 0.1 | -0.1 |
| Percentage of OtherNonoperatingIncomeExpenseExcludingMergerCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 |
| Value | 0.1 | 0.1 | 0.3 | 0.1 | 0.1 | 0.2 | 0.2 | 0.3 |
| Percentage of OtherNonoperatingIncomeExpenseExcludingMergerCosts | -33.3 | -2.1 | -0.3 | 0.1 | -5.3 | 0.7 | -1.1 | -20.0 |
| Period End | 2021-06-30 |
| Value | -700000.0 |
| Percentage of OtherOperatingLeaseCost | 100.0 |
| Period End | 2021-03-31 | 2020-09-30 | 2020-06-30 |
| Value | 200000.0 | 100000.0 | -500000.0 |
| Percentage of OtherVariableLeaseCost | 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 |
| Value | 100.0 | 99.0 | 1.0 | 1.0 | 99.0 | 1.0 | 1.0 |
| Percentage of PercentOfPerformanceTarget | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-07-31 |
| Value | 10.0 |
| Percentage of PercentageOfDifferenceBetweenPresentValueOfOldAndNewCashFlows | 100.0 |
| Period End | 2020-07-31 |
| Value | 10.0 |
| Percentage of PercentageOfDifferenceBetweenPresentValueOfOldAndNewCashFlows | 100.0 |
| Period End | 2020-07-31 |
| Value | 83.61 |
| Percentage of PercentageOfOutstandingExistingSubordinatedNotesValidlyTendered | 100.0 |
| Period End | 2020-07-31 |
| Value | 90.65 |
| Percentage of PercentageOfOutstandingExistingSubordinatedNotesValidlyTendered | 108.4 |
| Period End | 2020-07-31 |
| Value | 72.48 |
| Percentage of PercentageOfOutstandingExistingSubordinatedNotesValidlyTendered | 86.7 |
| Period End | 2020-07-31 |
| Value | 99.2 |
| Percentage of PercentageOfOutstandingExistingSubordinatedNotesValidlyTendered | 118.6 |
| Period End | 2020-07-31 |
| Value | 4.6 |
| Percentage of PercentageOfOutstandingSharesOfEntity | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 120.0 |
| Percentage of PercentageOfPerformanceStockUnitAwardVestingAsPercentageOfPerformanceTarget | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 80.0 |
| Percentage of PercentageOfPerformanceStockUnitAwardVestingAsPercentageOfPerformanceTarget | 0.0 | 66.7 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 200.0 |
| Percentage of PercentageOfPerformanceTargetForGrantOfPerformanceStockUnitAward | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 50.0 |
| Percentage of PercentageOfPerformanceTargetForGrantOfPerformanceStockUnitAward | 0.0 | 25.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 100.0 | 0 | 99.0 | 0 | 1.0 |
| Percentage of PercentageOfSalaryReduction | 100.0 | 0.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 20.0 | 0 | 19.8 | 0 | 0.2 |
| Percentage of PercentageOfSalaryReduction | 20.0 | 0.0 | 20.0 | 0.0 | 20.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2021-01-01 |
| Value | 68.0 | 27.0 | 30.0 |
| Percentage of PercentageOfTheatresReopened | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2021-01-01 |
| Value | 1.0 | 99.0 | 67.0 |
| Percentage of PercentageOfTheatresReopened | 1.5 | 366.7 | 223.3 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 28 |
| Percentage of ReclassificationOfCommitmentFeeAndDeferredCharges | 0.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 0.0 |
| Percentage of ReclassificationOfDerivativeLiabilityToAdditionalPaidInCapital | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 |
| Value | 0 | 0 | 0 | 100000.0 | 100000.0 | 100000.0 |
| Percentage of RelatedPartyReimbursements | 0.0 | 0.0 | 0.0 | 100.0 | 100.0 | 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 | 100000.0 | 0 | 100000.0 | 100000.0 | 200000.0 | 0 | 100000.0 | 100000.0 |
| Percentage of RelatedPartyReimbursements | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-09-30 |
| Value | 100000.0 |
| Percentage of RelatedPartyTransactionExpensesFromTransactions | 100.0 |
| Period End | 2020-09-30 |
| Value | -300000.0 |
| Percentage of RelatedPartyTransactionExpensesFromTransactions | -300.0 |
| Period End | 2020-10-30 |
| Value | 90.0 |
| Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingLevelInPeriodCovid19Percent | 100.0 |
| Period End | 2020-10-30 |
| Value | 7300000.0 |
| Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateIncrementalFairValue | 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 | 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 | -34.9 | 3.1 | -3.7 | -2.7 | -15.9 | 2.1 | 5.4 | 4.0 | 4.0 | 4.2 | 4.0 | 2.8 | 1.8 | -0.1 | 3.9 | 0.1 | 2.343 | 1.7 | 1.7 | 1.1 |
| Percentage of ShareBasedCompensationCashPortion | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2020-12-14 |
| Value | 8241800.0 |
| Percentage of StockIssuedDuringPeriodSharesCommitmentShares | 100.0 |
| Period End | 2020-12-14 |
| Value | 70 |
| Percentage of StockIssuedDuringPeriodValueCommitmentShares | 100.0 |
| Period End | 2021-06-30 | 2020-06-30 | 2020-03-31 |
| Value | 658.0 | 0 | 658.0 |
| Percentage of TangibleAssetImpairmentNumberOfScreens | 100.0 | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2020-06-30 | 2020-03-31 |
| Value | 57.0 | 0 | 57.0 |
| Percentage of TangibleAssetImpairmentNumberOfTheatres | 100.0 | 0.0 | 100.0 |
| Period End | 2021-03-31 |
| Value | 85.0 |
| Percentage of TheatreAttendancePercentageNeededToMaintainOperation | 100.0 |
| Period End | 2020-10-16 |
| Value | 10.0 |
| Percentage of TheatreLeftToReopenPercentage | 100.0 |
| Period End | 2021-03-31 |
| Value | 24.2 |
| Percentage of TheatreScreensOperatedPercentageDeclineFromPreviousYear | 100.0 |
| Period End | 2020-09-30 |
| Value | 39 |
| Percentage of ThirdPartyCosts | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -52.4 | 23 |
| Percentage of TotalDeferredLeaseAmountsChanges | 100.0 | 100.0 |
| Period End | 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 |
| Value | 3100000.0 | 3700000.0 | 2700000.0 | 2100000.0 | 5400000.0 | 4000000.0 | 4200000.0 | 4000000.0 | 2800000.0 | -300000.0 | 3000000.0 | -400000.0 |
| Percentage of ValueOfSharesIssuedStockBasedCompensation | 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 | 2018-09-30 | 2018-06-30 | 2018-03-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 |
| Value | 3100000.0 | 3700000.0 | 2700000.0 | 2100000.0 | 5400000.0 | 4000000.0 | 4200000.0 | 4000000.0 | 2800000.0 | -300000.0 | 3000000.0 | -400000.0 |
| Percentage of ValueOfSharesIssuedStockBasedCompensation | 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 | 3100000.0 | 3700000.0 | 2700000.0 | 2100000.0 | 5400000.0 | 4000000.0 |
| Percentage of ValueOfSharesIssuedStockBasedCompensation | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 |
| Value | 74 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature | 100.0 |
| Period End | 2020-09-30 |
| Value | 89 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature | 121.5 |
| Period End | 2020-09-30 |
| Value | 74 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature | 100.0 |
| Period End | 2020-09-30 |
| Value | -15.9 |
| Percentage of AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature | -21.5 |
| 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 | 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 | -17.8 | 42 | -17.8 | -10.8 | 3.5 | 3.1 | 3.2 | 3.1 | 2.8 | 2.2 | 2.3 | -0.4 | -0.8 | -0.9 | -0.8 | -0.8 | -0.8 | -0.3 | 0.027 | 0.058 | 0.057 | 0.059 | 0.134 | 0.014 | 2.226 | -1.566 | 1.622 | -1.528 | 2.13 | -1.392 |
| Percentage of AmortizationOfDebtDiscountPremium | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 0.0 |
| Percentage of AmortizationOfDebtDiscountPremium | -0.0 |
| Period End | 2020-07-31 |
| Value | 535 |
| Percentage of AmortizationOfDebtDiscountPremium | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 19 |
| Percentage of AmortizationOfDebtDiscountPremium | -0.0 | 45.2 |
| Period End | 2020-09-30 |
| Value | 30 |
| Percentage of AmortizationOfDebtDiscountPremium | -277.8 |
| Period End | 2020-12-31 |
| Value | 2.5 |
| Percentage of AmortizationOfDebtDiscountPremium | -14.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2018-03-31 | 2017-12-31 | 2017-09-30 |
| Value | 466 | 195 | 0.0 | 1851 | 16 | 3.6 | 0.0 |
| Percentage of AssetImpairmentCharges | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 8.1 | 21 | -11.5 | -17.7 | 7.5 | 18 | 17 | 15 | 11 | 18 | 20 | 16 | 25 | 39 | 17 |
| Percentage of ContractWithCustomerLiabilityRevenueRecognized | 100.0 | 100.0 | 100.0 | 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 |
| Value | -1.3 | 0.0 | -0.2 |
| Percentage of ContractWithCustomerLiabilityRevenueRecognized | 7.3 | 0.0 | -1.1 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2.0 | 0.5 | 1.6 | 2.0 | 0.0 | 4.8 |
| Percentage of ContractWithCustomerLiabilityRevenueRecognized | 24.7 | 2.3 | -13.9 | -11.3 | 0.0 | 26.2 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 3.9 | 0.8 | 1.6 | 0.9 | 0.0 | 12 |
| Percentage of ContractWithCustomerLiabilityRevenueRecognized | 48.1 | 3.7 | -13.9 | -5.1 | 0.0 | 68.3 |
| Period End | 2020-12-14 |
| Value | 13 |
| Percentage of ConversionOfStockSharesIssued1 | 100.0 |
| Period End | 2020-07-31 |
| Value | 600 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 100.0 |
| Period End | 2021-01-31 |
| Value | 600 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 0.0 |
| Period End | 2020-07-31 |
| Value | 2020 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 336.7 |
| Period End | 2020-09-14 |
| Value | 600 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 0.0 |
| Period End | 2020-12-31 |
| Value | 104 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 0.0 |
| Period End | 2021-01-27 |
| Value | 600 |
| Percentage of DebtConversionConvertedInstrumentAmount1 | 0.0 |
| Period End | 2020-12-31 |
| Value | 21 |
| Percentage of DebtConversionConvertedInstrumentSharesIssued1 | 100.0 |
| Period End | 2021-01-31 |
| Value | 44 |
| Percentage of DebtConversionConvertedInstrumentSharesIssued1 | 0.0 |
| Period End | 2021-01-27 |
| Value | 44 |
| Percentage of DebtConversionConvertedInstrumentSharesIssued1 | 0.0 |
| Period End | 2020-12-14 |
| Value | 104 |
| Percentage of DebtConversionOriginalDebtAmount1 | 100.0 |
| Period End | 2020-12-14 |
| Value | 100 |
| Percentage of DebtConversionOriginalDebtAmount1 | 95.7 |
| Period End | 2020-12-31 |
| Value | 115 |
| Percentage of DebtInstrumentConvertibleIfConvertedValueInExcessOfPrincipal | 100.0 |
| Period End | 2020-07-31 |
| Value | 555 |
| Percentage of DebtInstrumentIncreaseDecreaseForPeriodNet | 100.0 |
| Period End | 2021-01-31 |
| Value | 17 |
| Percentage of DebtInstrumentPeriodicPaymentInterest | 100.0 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 100.0 |
| Period End | 2020-07-31 |
| Value | 101.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 101.0 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 100.0 |
| Period End | 2020-07-31 |
| Value | 35.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 35.0 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 100.0 |
| Period End | 2020-07-31 |
| Value | 101.0 |
| Percentage of DebtInstrumentRedemptionPricePercentage | 101.0 |
| Period End | 2020-07-31 |
| Value | 110.5 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 100.0 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 102.62 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 92.9 |
| Period End | 2020-07-31 |
| Value | 105.25 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 95.2 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 103.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 93.2 |
| Period End | 2020-07-31 |
| Value | 106.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 95.9 |
| Period End | 2020-07-31 |
| Value | 23.9 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 21.6 |
| Period End | 2020-07-31 |
| Value | 0.241 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 0.2 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 102.62 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 92.9 |
| Period End | 2020-07-31 |
| Value | 100.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 90.5 |
| Period End | 2020-07-31 |
| Value | 101.0 |
| Percentage of DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed | 91.4 |
| 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 | 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 | -200000.0 | -200000.0 | 1000000.0 | 200000.0 | 300000.0 | 300000.0 | 400000.0 | 700000.0 | 500000.0 | 100000.0 | 600000.0 | 400000.0 | -100000.0 | 200000.0 | 0 | 300000.0 | 200000.0 | 100000.0 | 133000.0 | 199000.0 | 199000.0 | 199000.0 | -119000.0 | -86000.0 | -86000.0 | -17917000.0 | -854000.0 | -855000.0 | -854000.0 | -855000.0 |
| Percentage of DefinedBenefitPlanNetPeriodicBenefitCost | 100.0 | 100.0 | 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 |
| 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 |
| Value | 0.0 | -122.2 | 32 | -19.6 | -21.2 | 28 | 15 | -28.4 | -57.3 |
| Percentage of DerivativeGainLossOnDerivativeNet | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | 5.6 | -5.1 | 2.5 | 2.8 | 1.1 | -6.7 | 3.8 | -1.7 | -2.8 | 2.2 | -2.3 | -14.6 | 5.4 | 6.0 | -1.0 | 6.4 | 9.0 | 2.7 | 0.665 | -0.047 | -0.076 | 0.013 | -0.042 | -0.282 | -0.097 | 0.058 | -0.013 | 0.009 | 0.018 | -0.009 | -0.028 | 0.0 | -0.027 | -0.048 |
| Percentage of EffectOfExchangeRateOnCashAndCashEquivalents | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 |
| 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 | 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 | 0.0 | 0.3 | 0.0 | 3.7 | 6.1 | 7.6 | 18 | 4.7 | 1.8 | 10 | 4.3 | 3.1 | 3.5 | 24 | 12 | 6.5 | 2.2 | 24 | 18 | 3.4 | 0.6 | 17 |
| Percentage of EquityMethodInvestmentDividendsOrDistributions | 0.0 | 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 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2017-12-29 | 2017-06-30 |
| Value | 1.4 | 0.0 | 0.0 | 7.2 | 3.5 | 204 |
| Percentage of EquityMethodInvestmentOtherThanTemporaryImpairment | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0.0 | 0.0 | 7.2 |
| Percentage of EquityMethodInvestmentOtherThanTemporaryImpairment | 0.0 | 0.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 125 |
| Percentage of EquityMethodInvestmentOtherThanTemporaryImpairment | 8942.9 |
| 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 | 0.0 | 89 | 0.0 | -0.5 | 38 | 5.7 | -33.9 | -13.3 |
| Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 |
| Value | 178 |
| Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease | 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 |
| Value | 1.4 | 1.4 | 1.4 | 1.4 | 1.5 | 1.6 | 1.6 | 1.8 | 2.1 | 2.1 |
| Percentage of FinanceLeaseInterestExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 1.4 | 1.4 | 1.4 | 1.4 | 1.5 | 1.6 | 1.6 | 1.8 | 2.1 | 2.1 |
| Percentage of FinanceLeaseInterestExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 200000.0 | 1000000.0 | 1400000.0 | -1300000.0 | 1500000.0 | 1600000.0 | 1600000.0 | 1800000.0 | 2100000.0 | 2100000.0 |
| Percentage of FinanceLeaseInterestPaymentOnLiability | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 2.0 | 1.9 | 1.7 | 2.2 | 0.0 | 2.3 | 2.4 | 2.4 | 2.3 | 3.8 |
| Percentage of FinanceLeasePrincipalPayments | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 1300000.0 | 1300000.0 | 1500000.0 | 1600000.0 | 1700000.0 | 1900000.0 | 1900000.0 | 2100000.0 | 2500000.0 | 2700000.0 |
| Percentage of FinanceLeaseRightOfUseAssetAmortization | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 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 |
| Value | -3400000.0 | 3800000.0 | -100000.0 | 2100000.0 | -2000000.0 | -800000.0 | -100000.0 | -100000.0 | -500000.0 | -300000.0 | -100000.0 | -1000000.0 | -1200000.0 | -200000.0 | 500000.0 |
| Percentage of ForeignCurrencyTransactionGainLossRealized | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 | 2019-03-31 |
| Value | 3400000.0 | 3800000.0 | -2100000.0 | 2000000.0 | 500000.0 |
| Percentage of ForeignCurrencyTransactionGainLossRealized | -100.0 | 100.0 | -100.0 | -100.0 | -100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 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 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 |
| Value | 14 | 0.9 | 1.4 | 1.0 | 1.4 | 0.0 | 3.1 | 12 | 0.3 | 0.1 | 1.6 | 1.2 | -2.0 | 0.9 | 3.4 | 0.2 | -0.258 | -0.367 | 0.025 | 3.0 | 0.0 | 0.0 | 0.23 | -0.069 | 0.009 | 0.46 | -1.669 | -0.22 | -0.226 | 4.991 |
| Percentage of GainLossOnDispositionOfAssets | 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 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2019-06-30 | 2018-12-31 | 2018-09-30 |
| Value | 0.0 | -1.0 | -0.2 | -36.3 | -2.8 | 16 | -0.8 | 0.4 |
| Percentage of GainsLossesOnRestructuringOfDebt | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -18.7 | 52 | -86.1 | 70 | 50 | -106.8 |
| Percentage of GoodwillForeignCurrencyTranslationGainLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | -18.7 | 52 | 70 | 50 | -106.8 |
| Percentage of GoodwillForeignCurrencyTranslationGainLoss | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-09-30 |
| Value | 405 | 156 | 0.0 | 1744 | 0.0 |
| Percentage of GoodwillImpairmentLoss | 100.0 | 100.0 | 0.0 | 100.0 | 0.0 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 1124 | 0.0 | 151 | 0.0 | 1124 |
| Percentage of GoodwillImpairmentLoss | 0.0 | 0.0 | 96.4 | 0.0 | 64.5 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 619 | 405 | 5.6 | 0.0 | 619 |
| Percentage of GoodwillImpairmentLoss | 0.0 | 100.0 | 3.6 | 0.0 | 35.5 |
| Period End | 2020-09-30 | 2020-03-31 |
| Value | 151 | 1124 |
| Percentage of GoodwillImpairmentLoss | 96.4 | 64.5 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-03-31 |
| Value | 405 | 5.6 | 619 |
| Percentage of GoodwillImpairmentLoss | 100.0 | 3.6 | 35.5 |
| Period End | 2021-03-31 |
| Value | 3.7 |
| Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit | 100.0 |
| Period End | 2021-03-31 |
| Value | 3.7 |
| Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0.0 | 6.4 | 0.0 | 8.0 |
| Percentage of ImpairmentOfIntangibleAssetsFinitelived | 0.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2020-03-31 |
| Value | 8.0 | 0.0 | 6.4 | 8.0 |
| Percentage of ImpairmentOfIntangibleAssetsFinitelived | 0.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2.3 | 4.6 | 0.0 | 8.3 |
| Percentage of ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 0.2 | 0.1 | 0.0 | 2.4 |
| Percentage of ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill | 8.7 | 2.2 | 0.0 | 28.9 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 2.1 | 4.5 | 0.0 | 5.9 |
| Percentage of ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill | 91.3 | 97.8 | 0.0 | 71.1 |
| Period End | 2020-09-30 |
| Value | 0.1 |
| Percentage of ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill | 2.2 |
| Period End | 2020-09-30 |
| Value | 4.5 |
| Percentage of ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill | 97.8 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2018-12-31 | 2014-12-31 |
| Value | 58 | 28 | 0.0 | 91 | 13 | 3.149 |
| Percentage of ImpairmentOfLongLivedAssetsHeldForUse | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 15 | 0.0 | 0.0 | 9.9 |
| Percentage of ImpairmentOfLongLivedAssetsHeldForUse | 26.5 | 0.0 | 0.0 | 10.8 |
| Period End | 2021-06-30 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 81 | 43 | 28 | 0.0 | 81 |
| Percentage of ImpairmentOfLongLivedAssetsHeldForUse | 0.0 | 73.5 | 100.0 | 0.0 | 89.2 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 43 | 28 | 0.0 | 81 | 84 |
| Percentage of ImpairmentOfLongLivedAssetsHeldForUse | 73.5 | 100.0 | 0.0 | 89.2 | 0.0 |
| Period End | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 |
| Value | 15 | 0.0 | 0.0 | 9.9 |
| Percentage of ImpairmentOfLongLivedAssetsHeldForUse | 26.5 | 0.0 | 0.0 | 10.8 |
| 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 | 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 | -2.7 | -2.8 | -5.0 | -10.6 | -12.4 | -2.9 | 6.4 | 7.5 | 10 | 6.5 | 12 | 70 | 13 | -9.0 | 13 | -1.8 | -195.0 | -2.3 | 19 | 12 | 11 | 4.264 | 15 | 10 | 9.362 | 1.324 | 9.315 | 13 | 9.597 | -5.384 | 9.292 | 14 | 23 | 0.546 |
| 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 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 2.7 | 2.8 | 12 | 2.9 |
| Percentage of IncomeLossFromEquityMethodInvestments | -100.0 | -100.0 | -100.0 | -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 | 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 | 33 | -7.5 | -9.7 | -1.9 | 4.3 | 6.5 | 9.0 | 5.6 | 8.2 | 7.4 | 6.8 | 6.6 | 7.4 | 6.0 | 7.8 | 7.4 | 6.881 | 7.944 | 6.858 | 5.764 | 7.678 | 6.253 | 5.162 | 5.429 | 5.847 | 5.537 | 5.898 | 3.647 | 5.674 | 5.159 | 4.045 | 3.782 |
| Percentage of IncomeLossFromEquityMethodInvestments | -672.0 | 70.8 | 78.2 | 65.5 | 67.2 | 86.7 | 88.2 | 86.2 | 64.6 | 10.6 | 52.3 | -73.3 | 53.2 | -333.3 | -4.0 | -321.7 | 35.2 | 66.0 | 57.9 | 135.2 | 49.2 | 57.6 | 55.1 | 410.0 | 62.8 | 42.3 | 61.5 | -67.7 | 61.1 | 36.0 | 17.4 | 692.7 |
| Period End | 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 | -3.1 | -2.7 | -1.0 | 2.1 | 1.0 | 1.2 | 0.9 | 34 | 3.6 | 0.4 | 1.9 | -2.0 | 2.4 | -4.3 | -3.7 | 1.489 | 0.629 | 0.202 | 0.358 | 0.116 | 0.409 | 0.16 | 0.21 | 0.104 | 0.35 | 0.214 | 0.169 | 0.128 | 0.346 | 0.383 | -0.139 |
| Percentage of IncomeLossFromEquityMethodInvestments | 29.2 | 21.8 | 34.5 | 32.8 | 13.3 | 11.8 | 13.8 | 270.9 | 5.1 | 3.1 | -21.1 | -14.4 | -133.3 | 2.2 | 160.9 | 7.6 | 5.2 | 1.7 | 8.4 | 0.7 | 3.8 | 1.7 | 15.9 | 1.1 | 2.7 | 2.2 | -3.1 | 1.4 | 2.4 | 1.6 | -25.5 |
| Period End | 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 | -2.7 | -2.8 | -10.6 | -12.4 | -2.9 | 7.5 | 10 | 6.5 |
| Percentage of IncomeLossFromEquityMethodInvestments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | -2.7 | -2.8 | -5.1 | -10.7 | -18.4 | -11.2 | -12.9 | 2.4 | 7.6 | 37 | 5.9 | -11.3 | 3.8 | 14 | 7.3 | -21.2 | 1.766 | 8.629 | 11 | -6.199 | 7.042 | 2.294 | 8.077 | -7.81 | -1.485 | 7.947 | 7.805 | -14.165 | -1.409 | 6.103 | 20 | -5.828 |
| Percentage of IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 |
| Value | 20 | 96 | 85 | 116 | 6.4 | -105.7 | 54 |
| Percentage of IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | -2.0 | 13 | -9.5 | -17.7 | -20.4 | -29.2 | -34.1 | 21 | -4.1 | -14.5 | 9.3 | -15.6 | 3.4 | 3.3 | -21.9 | -4.6 | -2.5 | 10 | 29 | -3.335 | 1.342 | 1.69 | 3.04 | -8.831 | 6.349 | 2.277 | 4.336 | -1.839 | -0.459 | 2.244 | 6.87 | -3.419 | 2.966 | 2.498 |
| Percentage of IncreaseDecreaseInOtherOperatingAssets | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | -9.0 | 2.7 | 6.0 | 12 | -47.9 | -129.4 | 93 | -61.8 | 36 | -68.3 | 117 | -34.8 | 31 | -114.0 | 141 | -26.1 | 19 | -97.8 | 108 | -13.212 | 5.476 | -43.987 | 53 | -19.362 | 19 | -52.943 | 61 | -15.467 | -0.901 | -45.241 | 59 | -27.444 | 12 | -41.325 |
| Percentage of IncreaseDecreaseInReceivables | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 72 | 26 | 55 | 76 | 71 | 34 | 100 | 37 | 108 | 38 | 103 | 36 | 102 | 35 | 65 | 34 | 87 | 39 | 37 | 16 | 28 | 22 | 27 | 22 | 33 | 20 | 35 | 21 | 41 | 15 |
| Percentage of InterestPaid | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 0 | 200000.0 | 300000.0 | 300000.0 | 200000.0 | 300000.0 | 400000.0 | 200000.0 | 100000.0 | 300000.0 | 100000.0 | 100000.0 | 200000.0 | 100000.0 | 100000.0 | 200000.0 | 100000.0 | 100000.0 | 92000.0 | 100000.0 | 100000.0 | 46000.0 | 81000.0 | 35000.0 | 50000.0 | 37000.0 | 84000.0 | 60000.0 | 94000.0 | 77000.0 | 73000.0 | 165000.0 |
| Percentage of InterestPaidCapitalized | 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 |
| 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 | 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 | 6.3 | 2.0 | -6.1 | 4.1 | 1.3 | -9.4 | -2.7 | 0.5 | 2.1 | 16 | -1.2 | 0.7 | 1.5 | 5.2 | 1.0 | 16 | -0.6 | 5.3 | 0.552 | -0.176 | -0.2 | 10.0 | 1.076 | -0.163 |
| Percentage of InvestmentIncomeNet | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 |
| Value | -0.2 | 0.4 | 0.0 | 0.2 | 0.1 | 0.1 | 0.3 | 0.2 |
| Percentage of InvestmentIncomeNet | 3.3 | 9.8 | 0.0 | -2.1 | -3.7 | 20.0 | 14.3 | 1.2 |
| 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 |
| Value | 215 | 199 | 215 | 222 | 232 | 255 | 273 | 256 | 275 | 263 |
| Percentage of LeaseCost | 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 |
| Value | 36 |
| Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance | 100.0 |
| Period End | 2021-03-31 | 2020-09-30 |
| Value | 0.2 | 1.8 |
| Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance | 0.0 | 4.9 |
| Period End | 2021-03-31 | 2020-09-30 |
| Value | -4.0 | 34 |
| Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance | 0.0 | 95.1 |
| Period End | 2021-03-31 | 2020-09-30 |
| Value | 0.2 | 1.8 |
| Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance | 0.0 | 4.9 |
| Period End | 2021-06-30 | 2021-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2016-09-30 | 2016-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 |
| Value | 0.3 | 3.5 | -15.7 | 0.1 | 0.0 | 0.1 | 5.6 | 0.1 | 0.005 | 0.004 | 0.004 | 0.211 | 0.0 | 0.0 | 0.701 |
| Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 |
| 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 | 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 |
| Value | 21 | -51.0 | 89 | 11 | 55 | -93.6 | 70 | -68.1 | -9.3 | -25.4 | -20.5 | -5.6 | -109.1 | 11 | 22 | 34 | 77 | -2.0 | -4.375 | 0.389 | 0.581 | -0.196 | 1.568 | -2.076 | -1.098 | 2.141 | -11.552 |
| Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent | 7133.3 | -1457.1 | 0.0 | 0.0 | 0.0 | 0.0 | -450.3 | -68100.0 | 0.0 | -25400.0 | -366.1 | -5600.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 7780.0 | 14525.0 | -4900.0 | 743.1 | 0.0 | 0.0 | 305.4 | 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 | 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 |
| Value | 21 | -54.5 | 93 | 11 | 55 | -93.6 | 86 | -68.2 | -9.3 | -25.4 | -26.1 | -5.7 | -107.6 | 11 | 22 | 34 | 77 | -2.2 | -4.647 | 0.16 | 0.677 | -0.071 | 0.391 | 0.7 | -0.695 | 0.976 | 0.321 | 1.09 |
| Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent | 7033.3 | -1557.1 | 0.0 | 0.0 | 0.0 | 0.0 | -550.3 | -68200.0 | 0.0 | -25400.0 | -466.1 | -5700.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 3200.0 | 16925.0 | -1775.0 | 185.3 | 0.0 | 0.0 | 139.2 | 0.0 | 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 |
| Value | 190 | 175 | 194 | 198 | 203 | 216 | 217 | 219 | 220 | 218 |
| Percentage of OperatingLeaseCost | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 1.3 | 1.4 | 1.5 | 1.3 | 1.3 | 1.3 | 1.4000000000000004 | 1.4 | 1.4 | 1.3 |
| Percentage of OperatingLeaseCost | 0.7 | 0.8 | 0.8 | 0.7 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 |
| 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 |
| Value | -0.7 | 0.8 | 0.2 | 0.3 | 0.1 | 2.2 | 4.6 | 1.6 | 1.2 | 1.7 |
| Percentage of OperatingLeaseCost | -0.4 | 0.5 | 0.1 | 0.2 | 0.0 | 1.0 | 2.1 | 0.7 | 0.5 | 0.8 |
| 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 |
| Value | 2.3 | 2.3 | 3.1 | 3.8 | 3.8 | 3.9 | 3.9 | 3.5 | 3.5 | 3.5 |
| Percentage of OperatingLeaseCost | 1.2 | 1.3 | 1.6 | 1.9 | 1.9 | 1.8 | 1.8 | 1.6 | 1.6 | 1.6 |
| 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 | 2018-06-30 |
| Value | 205 | 192 | 207 | 214 | 224 | 237 | 241 | 238 | 245 | 242 | 204 | 203 | 199 |
| Percentage of OperatingLeaseExpense | 100.0 | 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 | 2020-09-30 | 2020-03-31 |
| Value | 37 | 19 | 60 |
| Percentage of OperatingLeaseImpairmentLoss | 100.0 | 100.0 | 100.0 |
| 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 |
| Value | 223 | 136 | 129 | 66 | 9.5 | 240 | 238 | 235 | 232 | 236 |
| Percentage of OperatingLeasePayments | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-06-30 | 2015-12-31 | 2015-09-30 |
| Value | 0.3 | 3.5 | -5.0 | 0.2 | 0.6 | 0.1 | -15.7 | 0.1 | 0.1 | 0.1 | 5.5 | 0.1 | -0.4 | -1.2 | -0.6 | 0.211 | 0.0 |
| Percentage of OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax | 100.0 | 100.0 | 100.0 | 100.0 | 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 |
| 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 | 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 | 21 | -54.7 | 93 | 11 | 55 | -93.6 | 86 | -68.2 | -9.3 | -25.4 | -26.1 | -5.7 | -107.6 | 11 | 22 | 34 | 77 | -2.2 | -4.647 | 0.16 | 0.677 | -0.071 | 0.391 | 0.7 | -0.695 | 0.976 | 0.321 | 1.09 | -0.599 | 0.166 | -0.162 | -1.624 | 0.331 | 1.634 |
| Percentage of OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-06-30 | 2016-03-31 | 2015-12-31 | 2015-09-30 | 2015-03-31 | 2014-12-31 | 2014-09-30 |
| Value | -900000.0 | -100000.0 | 0 | 100000.0 | 500000.0 | 0 | 0 | 1000000.0 | -71000.0 | 391000.0 | 700000.0 | 976000.0 | 321000.0 | 1090000.0 |
| Percentage of OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax | 100.0 | 100.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | 20 | -51.2 | 90 | 11 | 56 | -93.5 | 70 | -68.1 | -9.2 | -24.9 | -20.6 | -7.5 | -107.2 | 10 | 19 | 33 | 76 | -1.9 | -4.621 | 0.474 | 0.674 | -1.882 | 1.658 | -1.962 | -1.12 | -8.616 | -11.893 | -1.44 | 0.158 | 1.815 | 17 | -10.288 | 3.374 | 4.254 |
| Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 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 |
| Value | -51.0 | 11 | 56 | -93.5 | -68.1 | -9.2 | -24.9 | -20.5 | -7.5 | -107.0 | 10 | 19 | 33 | 76 | -1.9 | -4.621 | 0.474 | 0.674 | -1.882 | 1.658 | -1.962 | -1.12 | -8.616 | -11.893 |
| Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | 99.6 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 99.5 | 100.0 | 99.8 | 100.0 | 100.0 | 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 |
| Value | -0.2 |
| Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | 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 |
| Value | -51.0 | 11 | 56 | -93.5 | -68.1 | -9.2 | -24.9 |
| Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | 99.6 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 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 | 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 | 246 | 179 | 192 | 192 | 114 | 356 | 427 | 419 | 437 | 402 | 417 | 400 | 424 | 411 | 419 | 383 | 389 | 363 | 259 | 211 | 200 | 202 | 207 | 195 | 205 | 187 | 186 | 177 | 189 | 179 | 192 | 182 | 187 | 164 |
| Percentage of OtherCostAndExpenseOperating | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 54 | 51 | 65 | 32 | 25 | 33 | 26 | 37 | 43 | 46 | 43 | 48 | 43 | 44 | 20 | 32 | 46 | 34 | 31 | 19 | 20 | 18 | 16 | 18 | 17 | 4.941 | 18 | 12 | 15 | 18 | 37 | 26 | 17 | 16 |
| Percentage of OtherGeneralAndAdministrativeExpense | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2020-09-30 | 2020-03-31 | 2019-12-31 | 2019-03-31 | 2018-09-30 | 2016-06-30 |
| Value | 0.0 | 95 | 19 | 9.6 | 28 | 54 | -0.11 |
| Percentage of OtherNonoperatingExpense | 0.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 |
| Value | 54 | 52 | 43 |
| Percentage of PaidInKindInterest | 100.0 | 100.0 | 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 | 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 | -600000.0 | -1100000.0 | 100000.0 | -900000.0 | -600000.0 | -500000.0 | -100000.0 | 900000.0 | 1400000.0 | 300000.0 | -200000.0 | 600000.0 | -1300000.0 | 800000.0 | 1200000.0 | 1600000.0 | 5263000.0 | 1091000.0 | 412000.0 | -251000.0 | 691000.0 | 243000.0 | -721000.0 | 1636000.0 | 612000.0 | 601000.0 | -3323000.0 | 1783000.0 | 2026000.0 | 745000.0 | 3721000.0 | 956000.0 |
| Percentage of PaymentsForProceedsFromOtherInvestingActivities | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2018-12-31 | 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 | 2015-12-31 | 2015-09-30 | 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 | 0.3 | 19 | 0.2 | 5.9 | 9.2 | 0.1 | 0.2 | 0.5 | 1.2 | 12 | 3.8 | 0.3 | 2.0 | 27 | 65 | 0.044 | 0.276 | 0.501 | 9.274 | 0.969 | 0.0 | 0.078 | 0.306 | 7.568 | -0.423 | 1.438 | 7.936 | 0.175 |
| Percentage of PaymentsOfFinancingCosts | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 |
| Period End | 2021-06-01 |
| Value | 0.1 |
| Percentage of PaymentsOfFinancingCosts | 0.0 |
| Period End | 2020-09-30 |
| Value | 6.0 |
| Percentage of PaymentsOfFinancingCosts | 101.7 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.3 | 0.4 |
| Percentage of PaymentsOfFinancingCosts | 100.0 | 2.1 |
| Period End | 2021-06-30 | 2021-01-31 |
| Value | 0.3 | 0.4 |
| Percentage of PaymentsOfFinancingCosts | 100.0 | 0.0 |
| Period End | 2021-05-05 |
| Value | 3.8 |
| Percentage of PaymentsOfStockIssuanceCosts | 100.0 |
| Period End | 2021-01-31 | 2020-10-31 |
| Value | 14 | 1.3 |
| Percentage of PaymentsOfStockIssuanceCosts | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-09-30 |
| Value | 25 | 14 | 0.1 |
| Percentage of PaymentsOfStockIssuanceCosts | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-05-31 | 2021-01-31 |
| Value | 14 | 10 | 14 |
| Percentage of PaymentsOfStockIssuanceCosts | 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 |
| Value | 4100000.0 | 0 | 0 | 1000000.0 | 0 | 0 | 200000.0 | 1100000.0 | 0 | 0 | 0 | 1700000.0 | 0 | 0 | 0 | 6500000.0 |
| Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 | 2019-12-31 | 2019-09-30 |
| Value | 0.0 | 9.3 | 0.0 | 0.0 | 0.2 | 9.4 |
| Percentage of PaymentsToAcquireAssetsInvestingActivities | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 | 100.0 |
| Period End | 2021-06-01 |
| Value | 230 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2017-02-17 | 2017-02-13 |
| Value | 989 | 581 | 261 | 39 | 579 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-05-05 | 2017-02-17 | 2017-02-13 |
| Value | 153 | 39 | 579 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 |
| Period End | 2021-01-25 | 2021-01-31 | 2020-10-23 | 2020-10-31 |
| Value | 582 | 596 | 33 | 53 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-12-31 | 2020-09-30 |
| Value | 1014 | 596 | 269 | 2.9 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-05-31 | 2021-01-31 |
| Value | 587 | 427 | 596 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-03 | 2021-04-27 | 2021-01-25 | 2020-12-11 |
| Value | 587 | 427 | 244 | 352 |
| Percentage of ProceedsFromIssuanceOfCommonStock | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 534 |
| Percentage of ProceedsFromIssuanceOfDebt | 0.0 | 100.0 |
| Period End | 2020-12-31 | 2020-09-30 |
| Value | 0.0 | -220.0 |
| Percentage of ProceedsFromIssuanceOfMediumTermNotes | 0.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0.0 | 100 |
| Percentage of ProceedsFromIssuanceOfMediumTermNotes | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | -0.5 |
| Percentage of ProceedsFromMinorityShareholders | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | -100000.0 | -300000.0 |
| Percentage of ProceedsFromPaymentsToMinorityShareholders | 100.0 | 100.0 |
| 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 | 2017-09-30 | 2016-12-31 | 2016-09-30 | 2016-06-30 | 2016-03-31 |
| Value | 0.0 | -335.0 | -0.4 | -0.6 | -2.3 | 325 | -10.3 | 10 | -8.2 | -3.8 | 5.5 | 10.0 | -20.0 | 20 | -25.0 | -50.0 |
| Percentage of ProceedsFromRepaymentsOfLinesOfCredit | 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 |
| 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 | 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 | 2014-06-30 | 2014-03-31 | 2013-12-31 | 2013-09-30 | 2013-06-30 | 2013-03-31 |
| Value | -3.8 | 5.2 | 17 | 4.9 | 0.3 | 3.4 | 1.8 | 0.1 | 4.0 | 17 | 0.3 | 0.4 | 9.7 | 3.8 | 1.6 | 0.1 | 18 | 4.0 | 0.544 | 0.441 | 13 | 5.39 | 0.0 | 0.0 | 0.229 | 0.0 | 0.137 | -0.128 | -0.766 | -0.22 | -0.125 | 4.991 |
| Percentage of ProceedsFromSaleOfPropertyPlantAndEquipment | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2020-09-30 | 2020-06-30 | 2020-03-31 | 2018-03-31 | 2017-12-31 | 2017-09-30 | 2017-06-30 | 2017-03-31 | 2015-12-31 | 2015-09-30 | 2015-06-30 | 2015-03-31 | 2014-12-31 |
| Value | -0.2 | -0.6 | -0.1 | 1.2 | 2.5 | 0.0 | 0.6 | -0.1 | 0.014 | -0.007 | -0.006 | 10 | 0.466 |
| Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent | 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 | 2019-12-31 | 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 |
| Value | -1.0 | -0.2 | -0.6 | -0.1 | 0.1 | 0.0 | -0.1 | -0.5 | 0.0 | 1.9 | -2.1 | 1.4 | 2.8 | 1.0 | 0.6 | -0.1 | 0.246 | -0.085 | -0.093 | 1.686 | -0.09 | -0.114 | 0.022 | 10 | 0.341 |
| Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent | 0.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 116.7 | 112.0 | 0.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | -642.9 | 1628.6 | -366.7 | 98.9 | 73.2 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 0.4 | 0.3 | 0.8 | 2.4 |
| Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | 100.0 | 100.0 | 100.0 | 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 | 0.6 | 0.1 | 0.8 | 2.4 | 0.6 | 2.9 | 2.8 | 7.3 |
| Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | 0.0 | 0.0 | 100.0 | 100.0 | 0.0 | 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 |
| Value | 0.4 | -0.3 | -0.4 | 1.3 | 0.9 | 0.8 | 0.8 | 1.1 |
| Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | 0.0 | 0.0 | -50.0 | 54.2 | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 1.2 | 0.6 | 0.0 | 5.7 |
| Percentage of RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty | 100.0 | 100.0 | 0.0 | 100.0 |
| Period End | 2021-02-15 |
| Value | 89 |
| Percentage of RepaymentsOfLinesOfCredit | 100.0 |
| Period End | 2021-02-15 |
| Value | 12 |
| Percentage of RepaymentsOfLinesOfCredit | 14.3 |
| 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 | 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 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 8.5 | 3.4 | 3.5 | 3.4 | 3.4 | 3.5 | 3.5 | 3.4 | 3.5 | 2.2 | 2.201 | 2.202 | 2.201 | 2.202 | 0.0 | 1.938 | 1.937 | 1.938 | 1.937 | 1.938 | 1.937 | 1.938 | 1.937 | 1.937 | 1.938 | 2.001 |
| Percentage of RepaymentsOfSecuredDebt | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 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 |
| 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 | 0.0 | 0.2 | 0.0 | 3.6 | 7.7 | 5.5 | 5.3 | 3.9 |
| Percentage of RevenueFromRelatedParties | 0.0 | 100.0 | 0.0 | 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 | 0.1 | 0.0 | 2.1 | 3.8 | 4.2 | 3.5 |
| Percentage of RevenueFromRelatedParties | 50.0 | 0.0 | 58.3 | 69.1 | 79.2 | 89.7 |
| 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 |
| Value | 37 | 23 | 62 | 5.4 | 64 | 69 | 158 | 188 | 94 | 21 |
| Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 6.69 | 5.22 |
| Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 0 | 7.7 |
| Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue | 0.0 | 100.0 |
| Period End | 2021-06-01 |
| Value | 8.5 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 100.0 |
| Period End | 2020-12-14 |
| Value | 21 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 |
| Period End | 2021-05-05 | 2017-02-17 | 2017-02-13 |
| Value | 15 | 1.283255 | 19 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 | 0.0 | 0.0 |
| Period End | 2021-01-25 | 2021-01-31 | 2020-10-23 | 2020-10-31 |
| Value | 50 | 187 | 11 | 14 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2020-12-31 |
| Value | 40 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 |
| Period End | 2021-06-30 | 2021-05-31 | 2021-01-31 |
| Value | 11 | 43 | 187 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 | 0.0 | 0.0 |
| Period End | 2021-06-03 | 2021-04-27 | 2021-01-25 | 2020-12-11 |
| Value | 11 | 43 | 50 | 137 |
| Percentage of StockIssuedDuringPeriodSharesNewIssues | 0.0 | 0.0 | 0.0 | 0.0 |
| Period End | 2021-01-27 |
| Value | 5666000.0 |
| Percentage of StockIssuedDuringPeriodSharesShareBasedCompensationForfeited | 100.0 |
| Period End | 2020-09-30 |
| Value | 20 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 100.0 |
| Period End | 2020-09-30 |
| Value | 0.1 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 0.5 |
| Period End | 2020-09-30 |
| Value | 20 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 99.5 |
| Period End | 2020-09-30 |
| Value | 20 |
| Percentage of StockIssuedDuringPeriodValueAcquisitions | 100.0 |
| Period End | 2021-03-31 |
| Value | 606 |
| Percentage of StockIssuedDuringPeriodValueConversionOfConvertibleSecurities | 100.0 |
| Period End | 2021-03-31 |
| Value | 0.4 |
| Percentage of StockIssuedDuringPeriodValueConversionOfConvertibleSecurities | 0.1 |
| Period End | 2021-03-31 |
| Value | 606 |
| Percentage of StockIssuedDuringPeriodValueConversionOfConvertibleSecurities | 99.9 |
| Period End | 2021-03-31 |
| Value | 606 |
| Percentage of StockIssuedDuringPeriodValueConversionOfConvertibleSecurities | 100.0 |
| Period End | 2021-03-31 |
| Value | 500000.0 |
| Percentage of StockIssuedDuringPeriodValueOther | 100.0 |
| Period End | 2021-03-31 |
| Value | -500000.0 |
| Percentage of StockIssuedDuringPeriodValueOther | -100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 8.4 | 5.4 | 3.7 | 2.7 |
| Percentage of StockIssuedDuringPeriodValueShareBasedCompensationGross | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 | 2020-06-30 | 2020-03-31 |
| Value | 8.4 | 5.4 | 3.7 | 2.7 |
| Percentage of StockIssuedDuringPeriodValueShareBasedCompensationGross | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-06-30 | 2021-03-31 |
| Value | 8.4 | 5.4 |
| Percentage of StockIssuedDuringPeriodValueShareBasedCompensationGross | 100.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 |
| Value | -343.6 | -566.9 | -945.8 | -905.8 | -561.2 | -2176.3 | -13.5 | -54.8 | 23 | -130.2 | 113 | -100.4 | 22 | 17 |
| Percentage of UndistributedEarningsLossAvailableToCommonShareholdersDiluted | 100.0 | 100.0 | 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 | 2021-06-30 | 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 | 16 | 13 | 15 | 20 | 20 | 23 | 19 | 25 | 23 |
| Percentage of VariableLeaseCost | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 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 |
| Value | 4.8 | -0.2 | 0.1 | -0.5 | 7.0 | 19 | 7.4 | 19 | 10 |
| Percentage of VariableLeaseCost | 32.4 | -1.5 | 0.6 | -2.5 | 33.5 | 80.3 | 37.6 | 75.8 | 46.5 |
| Period End | 2020-09-30 |
| Value | 185 |
| Percentage of AccountsPayableForContractualAmountDue | 100.0 |
| Period End | 2021-06-30 | 2020-12-31 |
| Value | 69 | 138 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaid | 100.0 | 100.0 |
| Period End | 2021-06-30 |
| Value | 22 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaid | 33.2 |
| Period End | 2021-06-30 |
| Value | 15 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaid | 21.7 |
| Period End | 2021-06-30 |
| Value | 11 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaid | 17.1 |
| Period End | 2021-06-30 |
| Value | 19 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaid | 28.0 |
| Period End | 2020-12-31 |
| Value | 500000.0 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaidDeferredFinanceLease | 100.0 |
| Period End | 2020-12-31 |
| Value | 15 |
| Percentage of AccountsPayablesContractualRentPaymentsDueAndNotPaidDeferredVariableLease | 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 |
| Value | 6.7 | 12 | 11 | 11 | 8.452 | 8.591 | 9.211 | 10 |
| Percentage of AccruedCasualtyClaimsAndPremiumsCurrent | 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 |
| Value | 28 | 17 | 15 | 17 | 15 | 13 | 10 | 9.525 |
| Percentage of AccruedCasualtyClaimsAndPremiumsNoncurrent | 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 |
| Value | 28 | 43 | 39 | 30 | 39 | 12 | 10 | 21 |
| Percentage of AccruedPayrollAndVacationCurrent | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| Period End | 2021-03-31 | 2020-12-31 |
| Value | 11 | 30 |
| Percentage of ContingentLeaseLiabilities | 100.0 | 100.0 |
| 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 | 2018-06-30 | 2018-03-31 | 2017-12-31 |
| Value | 400 | 402 | 400 | 394 | 401 | 396 | 447 | 345 | 366 | 366 | 412 | 288 | 306 | 317 | 365 |
| Percentage of ContractsWithCustomersDeferredRevenue | 100.0 | 100.0 | 100.0 | 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 | 2021-06-30 | 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 |
| Value | 519 | 524 | 537 | 542 | 546 | 550 | 549 | 553 | 557 | 561 | 564 | 567 | 571 | 530 |
| Percentage of ContractsWithCustomersDeferredRevenue | 129.9 | 130.3 | 134.2 | 137.2 | 136.2 | 138.8 | 122.9 | 160.2 | 152.2 | 153.1 | 136.6 | 196.7 | 186.2 | 145.2 |
| Period End | 2020-12-31 | 2020-06-30 | 2020-03-31 | 2019-12-31 | 2019-09-30 | 2019-06-30 | 2019-03-31 | 2018-12-31 | 2018-09-30 | 2018-09-14 |
| Value | 529 | 522 | 518 | 515 | 520 | 510 | 541 | 524 | 642 | 587 |
| Percentage of ConvertibleDebtCarryingValue | 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 | 2019-12-31 | 2018-09-14 |
| Value | 526 | 515 | 524 |
| Percentage of ConvertibleDebtCarryingValue | 0.0 | 100.0 | 89.2 |
| Period End | 2020-12-31 |
| Value | 3000000.0 |
| Percentage of CurrentMaturitiesOfOperatingLeaseLiabilitiesDeferredFinanceLease | 100.0 |
| Period End | 2020-12-31 |
| Value | 67 |
| Percentage of CurrentMaturitiesOfOperatingLeaseLiabilitiesDeferredOperatingLease | 100.0 |