XNCR

Line plots across dimensions of each concept
Line plots across concepts
Tables

Plots across concepts

IncomeStatement

Balance Sheet

Assets

Current Assets

NonCurrent Assets

PropertyPlantAndEquipmentNet

Liabilities

Current Liabilities

Stockholders Equity

CashFlow

NetCashProvidedByUsedInOperatingActivities

NetCashProvidedByUsedInInvestingActivities

OperatingLeaseLiability

NonoperatingIncomeExpense

LesseeOperatingLeaseLiabilityPaymentsDue

Tables

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:CommonStockValue	███▇▇▇▇▇▇▇▇▇▁▁▁▁	0.584	0.583	0.58	0.573	0.572	0.57	0.569	0.567	0.565	0.564	0.563	0.562	0.47	0.47	0.468	0.467
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding		NA	NA	NA	57.266112	57.05961	56.946714	NA	56.643075	56.399255	58.009878	NA	58.313002	NA	46.929498	46.767759	NA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic		NA	NA	NA	57.266112	57.05961	56.946714	NA	56.643075	56.399255	56.302967	NA	55.97408	NA	46.929498	46.767759	NA
us-gaap:EarningsPerShareBasic	▄	0.9	NA	-0.24	-0.22	-0.61	-0.14	-0.47	-0.18	-0.28	1.42	-0.32	0.06	-0.25	-0.33	-0.15	-0.31
us-gaap:EarningsPerShareDiluted	▄	0.87	NA	-0.24	-0.22	-0.61	-0.14	-0.47	-0.18	-0.28	1.38	-0.32	0.05	-0.25	-0.33	-0.15	-0.31
us-gaap:EarningsPerShareBasicAndDiluted		NA	-0.04	NA	NA	NA	-0.14	NA	NA	NA	NA	NA	NA	0.16000000000000003	-0.48	-0.17	-0.31

		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	2017-12-31	2017-09-30	2017-06-30	2017-03-31

		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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
TTM Greenblatt ROC _ _	▄▂▂▂▁▃▁▂▂█▂▃▂▂▃▂	9.087	-15.672	-13.698	-16.722	-37.6	-8.777	-30.572	-14.276	-19.572	78.244	-21.082	0.651	-13.882	-16.49	-7.67	-15.519

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:AllocatedShareBasedCompensationExpense		NA	NA	8.539	8.318	8.231	6.512	7.227	9.514	9.303	5.856	5.075	6.12	3.44	3.605	3.448	3.158
us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType us-gaap:EmployeeStock		NA	NA	0.184	0.209	0.213	0.194	0.057	0.217	0.195	0.217	0.182	0.209	0.107	0.143	0.129	0.119
us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType us-gaap:EmployeeStockOption		NA	NA	6.873	6.624	6.667	5.882	6.914	9.117	8.946	5.525	4.814	5.832	3.333	3.462	3.319	3.039
us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType us-gaap:RestrictedStockUnitsRSU		NA	NA	1.497	1.485	1.351	0.436	0.207	0.18	0.162	0.114	0.079	0.079	NA	NA	NA	NA
us-gaap:AllocatedShareBasedCompensationExpense us-gaap:IncomeStatementLocation us-gaap:GeneralAndAdministrativeExpense		NA	NA	2.794	2.881	2.804	2.291	2.517	2.474	2.008	1.854	1.662	2.732	1.312	1.422	1.416	1.467
us-gaap:AllocatedShareBasedCompensationExpense us-gaap:IncomeStatementLocation us-gaap:ResearchAndDevelopmentExpense		NA	NA	5.764	5.437	5.427	4.221	4.661	7.04	7.295	4.002	3.413	3.388	2.128	2.183	2.032	1.691
us-gaap:ComprehensiveIncomeNetOfTax	▆▃▂▂▁▃▁▂▂█▂▃▂▂▃▂	52.136	-2.464	-14.184	-13.466	-34.591	-8.179	-27.187	-10.417	-14.75	81.361	-16.832	2.82	-12.554	-15.419	-6.929	-14.39
us-gaap:GeneralAndAdministrativeExpense	█▇▆▆▆▆▅▄▃▃▃▆▁▁▁▂	8.863	8.226	7.603	7.636	7.231	7.219	6.749	6.266	5.758	5.512	5.517	7.435	4.427	4.172	4.091	4.811
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest		NA	NA	-13.691	-12.55	-35.018	-8.074	-27.2	-10.574	-15.984	80.945	-18.199	3.15	-12.929	-15.389	-6.605	-14.465
us-gaap:InterestIncomeExpenseNet	▁▁▂▄▅▇▇██▆▆▆▃▃	0.147	0.215	0.712	1.423	2.09	3.039	3.418	3.699	3.615	2.886	2.807	2.642	1.047	1.045	NA	NA
us-gaap:InterestPaidNet	▆▅▁▅▆▇▁▅▄▅█▄▆▄▃▄	0.005	0.004	0.0	0.004	0.005	0.006	0.0	0.004	0.003	0.004	0.007	0.003	0.005	0.003	0.002	0.003
us-gaap:NetIncomeLoss	▆▃▂▂▁▃▁▃▂█▂▃▂▂▃▂	52.248	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80.045	-18.197	3.15	-11.843	-15.562	-6.885	-14.635
us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic	▆▃▂▂▁▃▁▃▂█▂▃▃▂▃▂	52.248	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80.045	-18.199	3.15	-3.072	-22.652	-7.725	-15.475
us-gaap:NonoperatingIncomeExpense	█▃▁▂▁▁▂▂▂▁▁▁▁▁▁▁	43.161	13.185	0.007	4.172	2.582	0.703	3.373	3.702	3.588	2.701	2.884	2.499	0.954	1.101	1.065	1.054
us-gaap:OperatingExpenses	█▆▇▇▇▅▄▄▄▄▃▃▂▂▁▁	58.36	49.637	55.552	52.088	50.689	41.162	34.089	36.036	39.057	33.695	32.647	28.388	24.823	23.58	21.01	19.859
us-gaap:OperatingIncomeLoss	▄▂▂▂▁▃▁▂▂█▂▃▂▂▃▂	9.087	-15.672	-13.698	-16.722	-37.6	-8.777	-30.572	-14.276	-19.572	78.244	-21.082	0.651	-13.882	-16.49	-7.67	-15.519
us-gaap:OtherNonoperatingIncomeExpense	▂█▂▃▂▁▂▂▂▂▂▂▂▂▂	-0.006	12.97	-0.705	2.749	0.492	-2.336	-0.045	0.003	-0.027	-0.185	0.077	-0.143	-0.093	0.056	0.03	NA
us-gaap:OtherNonoperatingIncomeExpense us-gaap:CounterpartyName,us-gaap:TypeOfArrangement xncr:CatabsisPharmaceuticalsInc,xncr:TechnologyLicenseAgreement		NA	12.9	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:OtherNonoperatingIncomeExpense us-gaap:CounterpartyName,us-gaap:TypeOfArrangement xncr:MiragenViridian,xncr:TechnologyLicenseAgreement		NA	0.1	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:ProfitLoss	▆▃▂▂▁▃▁▃▂█▂▃▂▂▃▂	52.248	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.225	-16.033	80.045	-18.199	3.151	-11.843	-15.563	-6.044	-15.475
us-gaap:ResearchAndDevelopmentExpense	█▆█▇▇▅▃▄▅▄▃▂▂▂▁▁	49.497	41.411	47.949	44.452	43.458	33.943	27.34	29.77	33.299	28.183	27.13	20.953	20.396	19.408	16.919	15.048
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax	▅▃▄▃▂▃▁▂▂█▂▃▃▁▂▁	67.447	33.965	41.854	35.366	13.089	32.385	3.516	21.76	19.485	111.939	11.564	29.039	30.15	0.0	12.5	3.5

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31

		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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:Assets	███▇▇▇▇███▅▅▁▁▂▂	695.602	692.737	703.244	646.349	644.72	666.963	670.25	686.244	684.753	697.003	576.732	585.586	390.102	398.255	416.164	418.303
us-gaap:Liabilities	▁▆█▃▃▃▃▃▃▄▂▁▆▆▇▇	48.664	109.125	130.8	77.866	74.075	73.958	77.049	76.007	76.662	87.438	55.051	53.313	108.056	107.716	114.799	114.555
us-gaap:LiabilitiesAndStockholdersEquity	███▇▇▇▇███▅▅▁▁▂▂	695.602	692.737	703.244	646.349	644.72	666.963	670.25	686.244	684.753	697.003	576.732	585.586	390.102	398.255	416.164	418.303
us-gaap:StockholdersEquity	█▇▇▆▇▇▇▇▇▇▆▆▁▁▁▁	646.938	583.612	572.444	568.483	570.645	593.005	593.201	610.237	608.091	609.565	521.681	532.273	282.046	290.539	301.365	303.748

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:AssetsCurrent	▆▇█▇▇▇▇▇▆▆▃▃▂▂▂▁	480.967	591.168	637.672	570.883	603.386	588.107	558.405	573.765	527.009	488.671	315.727	286.92	230.879	217.81	210.982	166.089
us-gaap:CashAndCashEquivalentsAtCarryingValue	▅█▇▃▅▄▃▃▂▁▂▂▁▁▁▁	115.842	176.965	163.544	58.094	109.534	73.808	50.312	51.189	32.557	21.858	26.246	34.996	16.528	13.634	11.22	13.561
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	▅█▇▃▅▄▃▃▂▁▂▂▁▁▁	115.842	176.965	163.544	58.094	109.534	73.808	50.312	51.189	32.557	21.858	26.246	34.996	16.528	13.634	11.22	NA
us-gaap:MarketableSecuritiesCurrent		NA	NA	NA	487.688	474.114	497.841	479.47	495.292	472.613	318.498	268.115	236.605	207.603	196.318	177.269	141.225
us-gaap:AccountsReceivableNetCurrent	▂▂▂▁▁▁▂▁▁█▁▁▁▁▂▁	14.825	12.525	11.443	9.534	8.925	6.825	21.574	4.349	10.13	137.676	10.187	2.462	1.142	0.831	14.876	6.938
us-gaap:PrepaidExpenseAndOtherAssetsCurrent	█▇▅▅▃▂▂▃▅▄▅▆▂▃▃▁	15.594	14.164	10.726	10.185	7.398	6.476	6.547	7.533	11.307	9.433	10.375	12.095	5.606	7.027	7.617	4.365

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:PropertyPlantAndEquipmentGross		NA	NA	38.713	NA	NA	NA	28.41	NA	NA	NA	21.239	NA	15.036	NA	NA	NA
us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:FurnitureAndFixtures		NA	NA	0.527	NA	NA	NA	0.492	NA	NA	NA	0.173	NA	0.152	NA	NA	NA
us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LeaseholdsAndLeaseholdImprovements		NA	NA	6.957	NA	NA	NA	6.831	NA	NA	NA	4.774	NA	4.01	NA	NA	NA
us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType xncr:ComputersSoftwareAndEquipment		NA	NA	31.229	NA	NA	NA	21.087	NA	NA	NA	16.292	NA	10.874	NA	NA	NA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment		NA	NA	17.031	NA	NA	NA	12.605	NA	NA	NA	9.426	NA	7.948	NA	NA	NA
us-gaap:PropertyPlantAndEquipmentNet	██▇▇▆▆▅▅▄▄▄▃▂▂▁▁	23.132	22.301	21.682	19.771	16.239	16.799	15.805	13.868	12.128	11.456	11.813	9.688	7.088	6.085	3.861	3.36
us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass us-gaap:Trademarks		NA	NA	0.399	NA	NA	NA	0.399	NA	NA	NA	0.399	NA	0.399	NA	NA	NA
us-gaap:IntangibleAssetsNetExcludingGoodwill	█▇▇▇▆▆▆▅▄▃▂▂▁▁▁▁	16.384	15.55	15.977	15.319	15.162	14.637	14.421	14.027	13.522	12.737	11.969	11.677	11.148	11.043	10.865	10.886
us-gaap:FiniteLivedIntangibleAssetsNet		NA	NA	7.146	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:OperatingLeaseRightOfUseAsset		NA	NA	10.6	NA	NA	NA	9.38	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:OtherAssetsNoncurrent	▄▇▁▆▆▇▁▇██▁▁▁▁▁▁	4.354	10.417	0.212	8.608	8.788	9.188	0.311	10.187	10.726	11.265	0.311	0.311	0.265	0.265	0.214	0.103
us-gaap:EquitySecuritiesFvNi	█▂▁▂▁▁	45.23	6.136	5.303	5.382	2.611	2.253	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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:AccountsPayableCurrent	▃▄▅█▆▆▆▄▅▂▁▃▃▃▄▁	7.112	7.663	8.954	13.109	10.513	10.313	10.189	8.304	8.994	5.485	3.797	5.983	6.869	6.602	7.379	4.275
us-gaap:AccruedLiabilitiesCurrent	█▅█▅▄▃▄▃▂▂▄▂▂▁▁▂	17.328	12.513	17.603	11.381	9.157	7.292	8.995	7.832	6.226	5.705	9.662	5.671	5.48	4.636	3.984	6.502
us-gaap:ContractWithCustomerLiabilityCurrent	▁▇█▃▃▄▃▄▄▅▃▃▅	19.2	77.821	92.615	43.84	44.685	46.176	45.205	45.579	45.478	59.244	40.079	40.079	60.118	NA	NA	NA
us-gaap:LiabilitiesCurrent	▁▆█▃▃▃▃▃▃▄▂▂▆▆▇▇	45.962	99.931	121.061	70.488	66.449	65.917	66.558	64.312	63.712	73.321	53.853	52.027	101.345	100.326	107.431	106.875
us-gaap:OperatingLeaseLiabilityCurrent	█▂▁▅▄▅▆▆▆▃	2.322	1.934	1.889	2.158	2.094	2.136	2.169	2.197	2.214	1.987	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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:OperatingLeaseLiabilityNoncurrent	▁▇█▅▆▆▆▇▇█	2.702	9.194	9.739	7.378	7.626	8.041	8.565	9.082	9.65	10.221	NA	NA	NA	NA	NA	NA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	▁▄██	0.707	1.415	2.269	2.269	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree	▁███	0.729	1.436	1.415	1.415	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour	▁███	0.688	1.396	1.436	1.436	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive		NA	1.48	1.396	1.33	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive		NA	3.861	5.342	1.238	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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:StockholdersEquity	█▇▇▆▇▇▇▇▇▇▆▆▁▁▁▁	646.938	583.612	572.444	568.483	570.645	593.005	593.201	610.237	608.091	609.565	521.681	532.273	282.046	290.539	301.365	303.748
us-gaap:CommonStockValue	███▇▇▇▇▇▇▇▇▇▁▁▁▁	0.584	0.583	0.58	0.573	0.572	0.57	0.569	0.567	0.565	0.564	0.563	0.562	0.47	0.47	0.468	0.467
us-gaap:AdditionalPaidInCapital	███▇▇▇▇▇▆▆▆▆▁▁▁▁	962.343	951.154	937.525	919.387	908.084	895.855	887.873	877.724	865.163	851.888	845.366	839.127	570.67	566.609	562.017	557.473
us-gaap:RetainedEarningsAccumulatedDeficit	▄▁▁▂▃▅▅▇▇█▄▅▆▆▇▇	-315.974	-368.222	-365.735	-352.044	-339.494	-304.476	-296.402	-269.49	-259.266	-243.232	-323.277	-305.078	-287.286	-275.443	-259.88	-252.996
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax	▅▅▅▆█▇▇██▆▃▁▂▃▃▃	-0.015	0.097	0.074	0.567	1.483	1.056	1.161	1.436	1.629	0.345	-0.971	-2.338	-1.808	-1.097	-1.24	-1.196
us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	█▁	9.35	8.293	NA	8.318	8.231	6.512	NA	9.514	9.303	5.856	5.075	6.12	3.44	3.604	3.449	3.158

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities	▂▁▃▂▁▃▂▂█▂▂▂▂▂▂▂	-9.654	-29.966	17.084	-3.866	-27.682	9.46	-19.577	-6.477	109.156	-18.728	-16.781	-10.311	-6.666	-3.509	-12.962	-10.546
us-gaap:NetCashProvidedByUsedInInvestingActivities	▃▆█▃▇▅▆▆▁▅▅▅▅▅▅▅	-53.309	38.048	78.779	-50.56	59.408	12.565	15.727	22.06	-102.43	13.673	6.866	5.862	8.939	4.933	9.525	8.553
us-gaap:NetCashProvidedByUsedInFinancingActivities	▂▅█▃▄▂▃▃▄▁▁▄▁▁▁▁	1.84	5.339	9.587	2.986	4.0	1.471	2.973	3.049	3.973	0.667	1.165	4.153	0.621	0.99	1.096	1.026
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	▁▄█▁▅▅▄▄▄▃▃▄▄▄	-61.123	13.421	105.45	-51.44	35.726	23.496	-0.877	18.632	10.699	-4.388	-8.75	-0.296	2.894	2.414	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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:DepreciationDepletionAndAmortization	█▇▇▆▆▆▅▄▄▄▃▃▂▂▁▁	1.753	1.638	1.532	1.446	1.443	1.373	1.225	1.07	1.007	0.996	0.883	0.816	0.61	0.556	0.454	0.41
us-gaap:IncreaseDecreaseInAccountsPayable	▄▄▁▇▅▅▇▄█▆▃▆▅▄█▅	-0.551	-1.291	-4.155	2.596	0.2	0.124	1.884	-0.689	3.508	1.689	-2.186	1.067	0.267	-0.778	3.105	0.395
us-gaap:NetCashProvidedByUsedInOperatingActivities	▂▁▃▂▁▃▂▂█▂▂▂▂▂▂▂	-9.654	-29.966	17.084	-3.866	-27.682	9.46	-19.577	-6.477	109.156	-18.728	-16.781	-10.311	-6.666	-3.509	-12.962	-10.546
us-gaap:NetIncomeLoss	▆▃▂▂▁▃▁▃▂█▂▃▂▂▃▂	52.248	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80.045	-18.197	3.15	-11.843	-15.562	-6.885	-14.635
us-gaap:ProfitLoss	▆▃▂▂▁▃▁▃▂█▂▃▂▂▃▂	52.248	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.225	-16.033	80.045	-18.199	3.151	-11.843	-15.563	-6.044	-15.475
us-gaap:ShareBasedCompensation	█▇▇▇▇▅▅██▄▃▄▁▁▁▁	9.35	8.293	8.558	8.318	8.231	6.512	7.178	9.514	9.303	5.856	5.075	6.12	3.44	3.604	3.449	3.158

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities	▃▆█▃▇▅▆▆▁▅▅▅▅▅▅▅	-53.309	38.048	78.779	-50.56	59.408	12.565	15.727	22.06	-102.43	13.673	6.866	5.862	8.939	4.933	9.525	8.553
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment	▄▄▅█▁▄▅▅▃▁▅▂▃▅▂▁	2.283	1.951	3.149	4.695	0.622	2.073	2.91	2.576	1.452	0.415	2.787	1.009	1.477	2.578	0.762	0.494

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities	▂▅█▃▄▂▃▃▄▁▁▄▁▁▁▁	1.84	5.339	9.587	2.986	4.0	1.471	2.973	3.049	3.973	0.667	1.165	4.153	0.621	0.99	1.096	1.026

		2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2017-06-30	2017-03-31

Common Stock Value

us-gaap:CommonStockValue

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	584000.0	583000.0	580000.0	573000.0	572000.0	570000.0	569000.0	567000.0	565000.0	564000.0	563000.0	562000.0	558000.0	556000.0	470000.0	470000.0	468000.0	467000.0	466000.0	411000.0	409000.0	407000.0	405000.0	405000.0	405000.0	404000.0	314000.0	314000.0	314000.0	314000.0	314000.0
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	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.2	0.5	0.4	0.4	0.4	0.4

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

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	2016-09-30	2016-06-30	2015-09-30	2015-06-30	2014-09-30	2014-06-30	2013-09-30	2013-06-30
Value	57	57	56	56	56	58	58	55	47	46	46	41	41	40	40	31	31	0.072302	12
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

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

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	2016-09-30	2016-06-30	2015-09-30	2015-06-30	2014-09-30	2014-06-30	2013-09-30	2013-06-30
Value	57	57	56	56	56	56	55	55	47	46	46	41	40	40	40	31	31	0.072302	0.072302
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

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

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	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	0.9	-0.24	-0.22	-0.61	-0.14	-0.47	-0.18	-0.28	1.42	-0.32	0.06	-0.46	-0.62	-0.25	-0.33	-0.15	-0.31	-0.21	-0.2	1.16	-0.16	0.19	-0.25	-0.22	-0.19	-0.04	-0.2	-0.16	-0.12	-0.37	-57.87	1341.7	-63.78
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

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

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	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	0.87	-0.24	-0.22	-0.61	-0.14	-0.47	-0.18	-0.28	1.38	-0.32	0.05	-0.46	-0.62	-0.25	-0.33	-0.15	-0.31	-0.21	-0.2	1.13	-0.16	0.19	-0.25	-0.22	-0.19	-0.04	-0.2	-0.16	-0.12	-0.37	-57.87	-3.88	-63.78
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

Earnings Per Share Basic And Diluted

us-gaap:EarningsPerShareBasicAndDiluted

Period End	2021-03-31	2020-03-31	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-03-31
Value	-0.04	-0.14	-0.46	-0.62	0.16	-0.48	-0.17	-0.31	-0.16
Percentage of EarningsPerShareBasicAndDiluted	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense

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	8.539	8.318	8.231	6.512	7.227	9.514	9.303	5.856	5.075	6.12	4.882	4.471	3.44	3.605	3.448	3.158	1.99	1.866	2.033	1.96	1.483	1.086	1.193	1.107	0.751	0.491	0.361	0.278	0.144	0.044	0.005	0.005
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	100.0	100.0	100.0	100.0	100.0	100.0	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	20.4	23.5	62.9	20.1	205.5	43.7	47.7	5.2	43.9	21.1	0.0	0.0	11.4	0.0	27.6	90.2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType

us-gaap:EmployeeStock

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	0.184	0.209	0.213	0.194	0.057	0.217	0.195	0.217	0.182	0.209	0.19	0.163	0.107	0.143	0.129	0.119
Percentage of AllocatedShareBasedCompensationExpense	2.2	2.5	2.6	3.0	0.8	2.3	2.1	3.7	3.6	3.4	3.9	3.6	3.1	4.0	3.7	3.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.4	0.6	1.6	0.6	1.6	1.0	1.0	0.2	1.6	0.7	0.0	0.0	0.4	0.0	1.0	3.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:EmployeeStock	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:EmployeeStockOption

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	6.873	6.624	6.667	5.882	6.914	9.117	8.946	5.525	4.814	5.832	4.614	4.276	3.333	3.462	3.319	3.039
Percentage of AllocatedShareBasedCompensationExpense	80.5	79.6	81.0	90.3	95.7	95.8	96.2	94.3	94.9	95.3	94.5	95.6	96.9	96.0	96.3	96.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	16.4	18.7	50.9	18.2	196.6	41.9	45.9	4.9	41.6	20.1	0.0	0.0	11.1	0.0	26.6	86.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:EmployeeStockOption	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:RestrictedStockUnitsRSU

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
Value	1.497	1.485	1.351	0.436	0.207	0.18	0.162	0.114	0.079	0.079	0.078	0.032
Percentage of AllocatedShareBasedCompensationExpense	17.5	17.9	16.4	6.7	2.9	1.9	1.7	1.9	1.6	1.3	1.6	0.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	3.6	4.2	10.3	1.3	5.9	0.8	0.8	0.1	0.7	0.3	0.0	0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RestrictedStockUnitsRSU	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:IncomeStatementLocation

us-gaap:GeneralAndAdministrativeExpense

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	2.794	2.881	2.804	2.291	2.517	2.474	2.008	1.854	1.662	2.732	1.688	1.617	1.312	1.422	1.416	1.467	0.893	0.874	0.874	0.952	0.59	0.593	0.52	0.514	0.273	0.276	0.164	0.128	0.014	0.02	0.003	0.003
Percentage of AllocatedShareBasedCompensationExpense	32.7	34.6	34.1	35.2	34.8	26.0	21.6	31.7	32.7	44.6	34.6	36.2	38.1	39.4	41.1	46.5	44.9	46.8	43.0	48.6	39.8	54.6	43.6	46.4	36.4	56.2	45.4	46.0	9.7	45.5	60.0	60.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	6.7	8.1	21.4	7.1	71.6	11.4	10.3	1.7	14.4	9.4	0.0	0.0	4.4	0.0	11.3	41.9	0.0	0.0	0.0	0.0	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 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	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:ResearchAndDevelopmentExpense

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	5.764	5.437	5.427	4.221	4.661	7.04	7.295	4.002	3.413	3.388	3.194	2.854	2.128	2.183	2.032	1.691	1.097	0.992	1.159	1.008	0.892	0.493	0.673	0.593	0.478	0.215	0.197	0.15	0.13	0.024	0.002	0.002
Percentage of AllocatedShareBasedCompensationExpense	67.5	65.4	65.9	64.8	64.5	74.0	78.4	68.3	67.3	55.4	65.4	63.8	61.9	60.6	58.9	53.5	55.1	53.2	57.0	51.4	60.1	45.4	56.4	53.6	63.6	43.8	54.6	54.0	90.3	54.5	40.0	40.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	13.8	15.4	41.5	13.0	132.6	32.4	37.4	3.6	29.5	11.7	0.0	0.0	7.1	0.0	16.3	48.3	0.0	0.0	0.0	0.0	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 RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ResearchAndDevelopmentExpense	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

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	52	-2.464	-14.184	-13.466	-34.591	-8.179	-27.187	-10.417	-14.75	81	-16.832	2.82	-25.676	-29.886	-12.554	-15.419	-6.929	-14.39	-10.256	-8.543	47	-5.779	7.247	-9.953	-8.923	-6.479	-1.349	-6.278
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.3	-7.3	-33.9	-38.1	-264.3	-25.3	-773.2	-47.9	-75.7	72.7	-145.6	9.7	0.0	0.0	-41.6	0.0	-55.4	-411.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:ComprehensiveIncomeNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	-0.112	0.023	-0.916	0.427	-0.105	-0.193	1.284	1.316	1.367	-0.33	0.193	-0.393	-0.711	0.143	-0.044	0.245	-1.191	-0.466	0.113	0.619	-0.51
Percentage of ComprehensiveIncomeNetOfTax	-0.2	-0.9	6.8	-1.2	1.3	1.9	-8.7	1.6	-8.1	-11.7	-0.8	1.3	5.7	-0.9	0.6	-1.7	11.6	5.5	0.2	-10.7	-7.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-0.2	0.1	-2.6	3.3	-0.3	-0.9	6.6	1.2	11.8	-1.1	0.0	0.0	-2.4	0.0	-0.4	7.0	0.0	0.0	0.0	0.0	0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax 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

us-gaap:RetainedEarnings

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	52	-2.487	-12.55	-35.018	-8.074	-10.224	-16.034	80	-18.199	3.15	-25.869	-29.493	-11.843	-15.563	-6.884	-14.635	-9.065	-8.077	47	-6.398	7.757
Percentage of ComprehensiveIncomeNetOfTax	100.2	100.9	93.2	101.2	98.7	98.1	108.7	98.4	108.1	111.7	100.8	98.7	94.3	100.9	99.4	101.7	88.4	94.5	99.8	110.7	107.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-35.5	-267.5	-24.9	-47.0	-82.3	71.5	-157.4	10.8	0.0	0.0	-39.3	0.0	-55.1	-418.1	0.0	0.0	0.0	0.0	0.0
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	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

General And Administrative Expense

us-gaap:GeneralAndAdministrativeExpense

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	8.863	8.226	7.603	7.636	7.231	7.219	6.749	6.266	5.758	5.512	5.517	7.435	4.958	4.562	4.427	4.172	4.091	4.811	3.108	3.007	3.043	3.95	3.439	3.233	2.524	2.764	1.962	2.182	1.594	1.723	1.311	0.842	0.793	0.746
Percentage of GeneralAndAdministrativeExpense	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	13.1	24.2	18.2	21.6	55.2	22.3	192.0	28.8	29.6	4.9	47.7	25.6	0.0	0.0	14.7	0.0	32.7	137.5	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

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
Value	-13.691	-12.55	-35.018	-8.074	-27.2	-10.574	-15.984	80	-18.199	3.15	-25.869	-29.493	-12.929	-15.389	-6.605	-14.465	-9.224	-8.675	48	-6.398	7.757	-10.037	-8.868
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-32.7	-35.5	-267.5	-24.9	-773.6	-48.6	-82.0	72.3	-157.4	10.8	0.0	0.0	-42.9	0.0	-52.8	-413.3	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Interest Income Expense Net

us-gaap:InterestIncomeExpenseNet

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	0.147	0.215	0.712	1.423	2.09	3.039	3.418	3.699	3.615	2.886	2.807	2.642	2.483	1.154	1.047	1.045
Percentage of InterestIncomeExpenseNet	100.0	100.0	100.0	100.0	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	0.2	0.6	1.7	4.0	16.0	9.4	97.2	17.0	18.6	2.6	24.3	9.1	0.0	0.0	3.5	0.0

Interest Paid Net

us-gaap:InterestPaidNet

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	5000.0	4000.0	0	4000.0	5000.0	6000.0	0	4000.0	3000.0	4000.0	7000.0	3000.0	3000.0	3000.0	5000.0	3000.0	2000.0	3000.0
Percentage of InterestPaidNet	100.0	100.0	0.0	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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.1

Net Income Loss

us-gaap:NetIncomeLoss

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	52	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80	-18.197	3.15	-25.869	-29.493	-11.843	-15.562	-6.885	-14.635	-9.065	-8.077	47	-6.398	7.757	-10.037	-8.868	-6.444	-1.349	-6.278	-5.044	-3.751
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	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-32.7	-35.5	-267.5	-24.9	-765.4	-47.0	-82.3	71.5	-157.4	10.8	0.0	0.0	-39.3	0.0	-55.1	-418.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

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	2014-12-31	2014-09-30	2014-06-30	2013-12-31	2013-09-30	2013-06-30
Value	52	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80	-18.199	3.15	-25.869	-29.493	-3.072	-22.652	-7.725	-15.475	-1.349	-6.278	-5.044	-3.703	-4.184	97
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-32.7	-35.5	-267.5	-24.9	-765.4	-47.0	-82.3	71.5	-157.4	10.8	0.0	0.0	-10.2	0.0	-61.8	-442.1	0.0	0.0	0.0	0.0	0.0	0.0

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

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	43	13	0.007	4.172	2.582	0.703	3.373	3.702	3.588	2.701	2.884	2.499	2.421	1.156	0.954	1.101	1.065	1.054	0.804	0.58	0.358	0.335	0.319	0.275	0.118	0.034	0.001	0.009	0.009	0.016	0.007	0.008	-49.103	-0.651
Percentage of NonoperatingIncomeExpense	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	64.0	38.8	0.0	11.8	19.7	2.2	95.9	17.0	18.4	2.4	24.9	8.6	0.0	0.0	3.2	0.0	8.5	30.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Operating Expenses

us-gaap:OperatingExpenses

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	58	49	55	52	50	41	34	36	39	33	32	28	28	30	24	23	21	19	16	17	17	13	14	13	10.0	7.969	7.014	7.135	5.877	5.951	5.454	5.005	4.927	5.306
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	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	86.5	146.1	132.7	147.3	387.3	127.1	969.5	165.6	200.4	30.1	282.3	97.8	0.0	0.0	82.3	0.0	168.1	567.4	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Operating Income Loss

us-gaap:OperatingIncomeLoss

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	9.087	-15.672	-13.698	-16.722	-37.6	-8.777	-30.572	-14.276	-19.572	78	-21.082	0.651	-28.29	-30.649	-13.882	-16.49	-7.67	-15.519	-10.028	-9.255	48	-6.733	7.438	-10.312	-8.986	-6.478	-1.35	-6.287	-5.053	-3.767	-3.71	-1.843	-1.006	-3.961
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	13.5	-46.1	-32.7	-47.3	-287.3	-27.1	-869.5	-65.6	-100.4	69.9	-182.3	2.2	0.0	0.0	-46.0	0.0	-61.4	-443.4	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

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	2016-12-31	2016-09-30	2015-12-31	2015-09-30	2015-06-30	2014-12-31	2014-09-30	2014-06-30	2013-12-31	2013-09-30	2013-06-30
Value	-0.006	12	-0.705	2.749	0.492	-2.336	-0.045	0.003	-0.027	-0.185	0.077	-0.143	-0.062	0.002	-0.093	0.056	0.03	0.001	0.003	-0.452	-0.397	-0.168	0.001	0.009	0.001	0.001	0.004	0.003
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	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-0.0	38.2	-1.7	7.8	3.8	-7.2	-1.3	0.0	-0.1	-0.2	0.7	-0.5	0.0	0.0	-0.3	0.0	0.2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:OtherNonoperatingIncomeExpense us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CatabsisPharmaceuticalsInc, xncr:TechnologyLicenseAgreement

Period End	2021-03-31
Value	12
Percentage of OtherNonoperatingIncomeExpense	99.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	38.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:CatabsisPharmaceuticalsInc xncr:TechnologyLicenseAgreement	0.0

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement

Period End	2021-03-31
Value	0.1
Percentage of OtherNonoperatingIncomeExpense	0.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:MiragenViridian xncr:TechnologyLicenseAgreement	0.0

Profit Loss

us-gaap:ProfitLoss

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
Value	52	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.225	-16.033	80	-18.199	3.151	-25.868	-29.493	-11.843	-15.563	-6.044	-15.475	-9.065	-8.077
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	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-32.7	-35.5	-267.5	-24.9	-765.4	-47.0	-82.3	71.5	-157.4	10.9	0.0	0.0	-39.3	0.0	-48.4	-442.1	0.0	0.0

Research And Development Expense

us-gaap:ResearchAndDevelopmentExpense

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	49	41	47	44	43	33	27	29	33	28	27	20	23	26	20	19	16	15	13	14	14	10	10	10	7.476	5.205	5.052	4.953	4.283	4.228	4.143	4.163	4.134	4.56
Percentage of ResearchAndDevelopmentExpense	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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	73.4	121.9	114.6	125.7	332.0	104.8	777.6	136.8	170.9	25.2	234.6	72.2	0.0	0.0	67.6	0.0	135.4	429.9	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

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	2017-12-31	2017-09-30	2017-06-30	2017-03-31
Value	67	33	41	35	13	32	3.516	21	19	111	11	29	30	0.0	12	3.5
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	0.0	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	0.0	100.0	100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CounterpartyName

xncr:Aimmune

Period End	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	0.0	0.0	0.0	9.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	0.0	0.0	29.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	0.0	0.0	29.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Aimmune	0.0	0.0	0.0	100.0

xncr:AlexionPharmaceuticalsInc

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	2018-12-31	2018-09-30
Value	5.2	5.3	14	4.3	3.8	3.3	2.5	5.4	5.1	11	9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	7.7	15.6	35.1	12.2	29.0	10.2	71.1	24.8	26.2	95.1	31.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	7.7	15.6	35.1	12.2	29.0	10.2	71.1	24.8	26.2	95.1	31.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:AlexionPharmaceuticalsInc	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:Astellas

Period End	2020-12-31	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30
Value	2.6	0.0	0.7	0.3	0.2	0.0	13
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	6.2	0.0	5.3	0.9	5.7	0.0	70.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	6.2	0.0	5.3	0.9	5.7	0.0	70.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Astellas	100.0	0.0	100.0	100.0	100.0	0.0	100.0

xncr:Genentech

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	0.2	1.2	0.9	0.8	0.7	0.7	0.7	0.6	112
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	3.4	0.6	2.9	2.5	6.1	2.2	19.9	3.2	3.1	100.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	3.4	0.6	2.9	2.5	6.1	2.2	19.9	3.2	3.1	100.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Genentech	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:Gilead

Period End	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	0.0	0.0	7.5	6.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	0.0	57.3	18.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	0.0	57.3	18.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Gilead	0.0	0.0	100.0	100.0

xncr:Janssen

Period End	2021-06-30	2021-03-31
Value	16	14
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	24.0	43.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	24.0	43.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Janssen	100.0	100.0

xncr:MorphoSys

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	1.2	13	1.3	25	0.0	12
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	1.8	40.9	3.1	71.3	0.0	38.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	1.8	40.9	3.1	71.3	0.0	38.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:MorphoSys	100.0	100.0	100.0	100.0	0.0	100.0

xncr:Novartis

Period End	2021-06-30	2019-12-31	2019-09-30	2018-12-31	2018-09-30
Value	41	0.0	10.0	0.0	20
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	60.9	0.0	46.0	0.0	68.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	60.9	0.0	46.0	0.0	68.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Novartis	100.0	0.0	100.0	0.0	100.0

xncr:OmerosCorporation

Period End	2020-12-31	2020-09-30
Value	0.0	5.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	14.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	0.0	14.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:OmerosCorporation	0.0	100.0

xncr:VirBiotechnology

Period End	2021-06-30	2020-12-31	2020-09-30	2020-06-30	2019-12-31	2019-09-30
Value	1.4	0.0	0.0	0.3	0.1	0.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.1	0.0	0.0	2.3	2.8	3.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.1	0.0	0.0	2.3	2.8	3.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:VirBiotechnology	100.0	0.0	0.0	100.0	100.0	100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:OmerosCorporation, xncr:TechnologyLicenseAgreement

Period End	2020-09-30
Value	5.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	14.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	14.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:OmerosCorporation xncr:TechnologyLicenseAgreement	100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService

us-gaap:License

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	22	5.0	7.5	15	0.0	0.5	-0.1	111
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	52.8	14.1	57.3	48.2	0.0	2.3	-0.5	99.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	52.8	14.1	57.3	48.2	0.0	2.3	-0.5	99.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:License	100.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0

us-gaap:Royalty

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	7.3	6.7	6.1	4.5	3.8	3.3	2.5	1.4	1.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	10.8	19.7	14.6	12.7	29.0	10.2	71.1	6.4	5.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	10.8	19.7	14.6	12.7	29.0	10.2	71.1	6.4	5.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Royalty	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:Collaboration

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	58	14	1.3	0.9	1.5	1.0	1.1	0.6	14	0.3	0.1	20
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	86.9	43.6	3.1	2.5	11.5	3.1	31.3	2.8	73.9	0.3	0.9	68.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	86.9	43.6	3.1	2.5	11.5	3.1	31.3	2.8	73.9	0.3	0.9	68.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Collaboration	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:Milestone

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	2018-12-31	2018-09-30
Value	1.5	12	12	25	0.3	12	-0.1	19	4.0	11	9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.2	36.8	29.6	70.7	2.3	38.6	-2.8	88.7	20.5	99.4	31.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.2	36.8	29.6	70.7	2.3	38.6	-2.8	88.7	20.5	99.4	31.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax xncr:Milestone	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

Assets

us-gaap:Assets

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	695	692	703	646	644	666	670	686	684	697	576	585	591	612	390	398	416	418	428	322	334	193	206	211	172	178	67	70	76	82	87
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

Liabilities

us-gaap:Liabilities

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	48	109	130	77	74	73	77	76	76	87	55	53	72	74	108	107	114	114	114	119	125	35	44	58	10	9.337	8.533	11	10	12	13
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	7.0	15.8	18.6	12.0	11.5	11.1	11.5	11.1	11.2	12.5	9.5	9.1	12.2	12.2	27.7	27.0	27.6	27.4	26.7	37.2	37.6	18.1	21.5	27.5	6.1	5.2	12.6	15.7	14.2	15.1	15.8

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

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	695	692	703	646	644	666	670	686	684	697	576	585	591	612	390	398	416	418	428	322	334	193	206	211	172	178	67	70	76	82	87
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

Stockholders Equity

us-gaap:StockholdersEquity

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	2011-12-31
Value	646	583	572	568	570	593	593	610	608	609	521	532	519	537	282	290	301	303	313	202	208	158	162	153	162	169	59	59	65	70	73	-166.268	-157.703
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	100.0
Percentage of Assets	93.0	84.2	81.4	88.0	88.5	88.9	88.5	88.9	88.8	87.5	90.5	90.9	87.8	87.8	72.3	73.0	72.4	72.6	73.3	62.8	62.4	81.9	78.5	72.5	93.9	94.8	87.4	84.3	85.8	84.9	84.2	0.0	0.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome

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
Value	-0.015	0.097	0.074	0.567	1.483	1.056	1.161	1.436	1.629	0.345	-0.971	-2.338	-2.008	-2.201	-1.808	-1.097	-1.24	-1.196	-1.441	-0.25	0.216	0.103	-0.516	-0.006	-0.09	-0.035
Percentage of StockholdersEquity	-0.0	0.0	0.0	0.1	0.3	0.2	0.2	0.2	0.3	0.1	-0.2	-0.4	-0.4	-0.4	-0.6	-0.4	-0.4	-0.4	-0.5	-0.1	0.1	0.1	-0.3	-0.0	-0.1	-0.0
Percentage of Assets	-0.0	0.0	0.0	0.1	0.2	0.2	0.2	0.2	0.2	0.0	-0.2	-0.4	-0.3	-0.4	-0.5	-0.3	-0.3	-0.3	-0.3	-0.1	0.1	0.1	-0.2	-0.0	-0.1	-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

us-gaap:AdditionalPaidInCapital

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	2013-12-31	2012-12-31	2011-12-31
Value	962	951	937	919	908	895	887	877	865	851	845	839	828	821	570	566	562	557	552	431	428	426	424	422	421	419	302	300	1.043	1.014
Percentage of StockholdersEquity	148.8	163.0	163.8	161.7	159.1	151.1	149.7	143.8	142.3	139.8	162.0	157.6	159.6	152.8	202.3	195.0	186.5	183.5	176.1	213.0	205.6	268.4	261.1	275.4	259.8	247.7	511.0	409.1	-0.6	-0.6
Percentage of Assets	138.3	137.3	133.3	142.2	140.8	134.3	132.5	127.9	126.3	122.2	146.6	143.3	140.1	134.2	146.3	142.3	135.0	133.3	129.0	133.8	128.3	219.8	205.0	199.7	244.0	234.8	446.7	344.5	0.0	0.0
Percentage of Assets us-gaap:AdditionalPaidInCapital	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CommonStock

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	2013-12-31	2012-12-31	2011-12-31
Value	0.584	0.583	0.58	0.573	0.572	0.57	0.569	0.567	0.565	0.564	0.563	0.562	0.558	0.556	0.47	0.47	0.468	0.467	0.466	0.411	0.409	0.407	0.405	0.405	0.405	0.404	0.314	0.314	0.001	0.001
Percentage of StockholdersEquity	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.1	0.2	0.2	0.3	0.2	0.3	0.2	0.2	0.5	0.4	-0.0	-0.0
Percentage of Assets	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.2	0.5	0.4	0.0	0.0
Percentage of Assets us-gaap:CommonStock	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:RetainedEarnings

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	2013-12-31	2012-12-31	2011-12-31
Value	-315.974	-368.222	-365.735	-352.044	-339.494	-304.476	-296.402	-269.49	-259.266	-243.232	-323.277	-305.078	-308.229	-282.361	-287.286	-275.443	-259.88	-252.996	-237.96	-228.895	-220.818	-267.983	-261.585	-269.342	-259.305	-250.437	-243.993	-227.571	-167.312	-158.718
Percentage of StockholdersEquity	-48.8	-63.1	-63.9	-61.9	-59.5	-51.3	-50.0	-44.2	-42.6	-39.9	-62.0	-57.3	-59.4	-52.5	-101.9	-94.8	-86.2	-83.3	-75.8	-113.1	-105.9	-168.7	-161.0	-175.7	-160.0	-147.9	-411.5	-309.5	100.6	100.6
Percentage of Assets	-45.4	-53.2	-52.0	-54.5	-52.7	-45.7	-44.2	-39.3	-37.9	-34.9	-56.1	-52.1	-52.1	-46.1	-73.6	-69.2	-62.4	-60.5	-55.5	-71.1	-66.1	-138.2	-126.4	-127.4	-150.3	-140.2	-359.7	-260.6	0.0	0.0
Percentage of Assets us-gaap:RetainedEarnings	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Assets Current

us-gaap:AssetsCurrent

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	480	591	637	570	603	588	558	573	527	488	315	286	269	470	230	217	210	166	141	110	243	94	97	129	69	145	57	61	66	73	78
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	69.1	85.3	90.7	88.3	93.6	88.2	83.3	83.6	77.0	70.1	54.7	49.0	45.6	76.9	59.2	54.7	50.7	39.7	33.1	34.4	72.9	48.9	47.2	61.4	40.4	81.2	85.1	86.2	87.3	88.7	89.4

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

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	2011-12-31
Value	115	176	163	58	109	73	50	51	32	21	26	34	35	251	16	13	11	13	14	14	7.877	8.15	12	57	11	119	54	60	66	72	77	9.621	11	3.408	2.312	14
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	16.7	25.5	23.3	9.0	17.0	11.1	7.5	7.5	4.8	3.1	4.6	6.0	6.0	41.1	4.2	3.4	2.7	3.2	3.4	4.6	2.4	4.2	6.1	27.3	6.5	66.6	80.6	86.0	86.7	87.9	89.3	0.0	0.0	0.0	0.0	0.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:CashAndCashEquivalents

us-gaap:MoneyMarketFunds

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	71	165	158	34	103	49	32	30	22	15	18	15	31	247	5.175	9.33	10	11	12	10	6.969	6.815	9.453	9.904
Percentage of CashAndCashEquivalentsAtCarryingValue	61.9	93.4	97.2	59.4	94.2	67.5	63.6	59.8	70.3	71.5	69.6	44.7	88.2	98.5	31.3	68.4	89.7	81.5	83.5	73.4	88.5	83.6	75.1	17.2
Percentage of Assets	10.3	23.9	22.6	5.3	16.0	7.5	4.8	4.5	3.3	2.2	3.2	2.7	5.3	40.5	1.3	2.3	2.4	2.6	2.8	3.4	2.1	3.5	4.6	4.7
Percentage of Assets us-gaap:MoneyMarketFunds	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:CashAndCashEquivalents, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:MoneyMarketFunds, us-gaap:FairValueInputsLevel1

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
Value	71	165	158	34	103	49	32	30	22	15	18	15	31	247	5.175	9.33	10	11	12	10	6.969	6.815	9.453	9.904	1.379	2.04
Percentage of CashAndCashEquivalentsAtCarryingValue	61.9	93.4	97.2	59.4	94.2	67.5	63.6	59.8	70.3	71.5	69.6	44.7	88.2	98.5	31.3	68.4	89.7	81.5	83.5	73.4	88.5	83.6	75.1	17.2	12.3	1.7
Percentage of Assets	10.3	23.9	22.6	5.3	16.0	7.5	4.8	4.5	3.3	2.2	3.2	2.7	5.3	40.5	1.3	2.3	2.4	2.6	2.8	3.4	2.1	3.5	4.6	4.7	0.8	1.1
Percentage of Assets us-gaap:MoneyMarketFunds us-gaap:FairValueInputsLevel1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	158	32	18	5.175	12	9.453
Percentage of CashAndCashEquivalentsAtCarryingValue	97.2	63.6	69.6	31.3	83.5	75.1
Percentage of Assets	22.6	4.8	3.2	1.3	2.8	4.6
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring us-gaap:MoneyMarketFunds	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	158	32	18	5.175	12	9.453
Percentage of CashAndCashEquivalentsAtCarryingValue	97.2	63.6	69.6	31.3	83.5	75.1
Percentage of Assets	22.6	4.8	3.2	1.3	2.8	4.6
Percentage of Assets us-gaap:FairValueMeasurementsRecurring us-gaap:MoneyMarketFunds	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:InvestmentType

us-gaap:CashAndCashEquivalents

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	71	165	158	34	103	49	32	30	22	15	18	15	31	247	5.175
Percentage of CashAndCashEquivalentsAtCarryingValue	61.9	93.4	97.2	59.4	94.2	67.5	63.6	59.8	70.3	71.5	69.6	44.7	88.2	98.5	31.3
Percentage of Assets	10.3	23.9	22.6	5.3	16.0	7.5	4.8	4.5	3.3	2.2	3.2	2.7	5.3	40.5	1.3
Percentage of Assets us-gaap:CashAndCashEquivalents	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:MoneyMarketFunds

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	71	165	158	34	103	49	32	30	22	15	18	15	31	247	5.175
Percentage of CashAndCashEquivalentsAtCarryingValue	61.9	93.4	97.2	59.4	94.2	67.5	63.6	59.8	70.3	71.5	69.6	44.7	88.2	98.5	31.3
Percentage of Assets	10.3	23.9	22.6	5.3	16.0	7.5	4.8	4.5	3.3	2.2	3.2	2.7	5.3	40.5	1.3
Percentage of Assets us-gaap:MoneyMarketFunds	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

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	2016-12-31	2015-12-31
Value	115	176	163	58	109	73	50	51	32	21	26	34	35	251	16	13	11	14	12
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
Percentage of Assets	16.7	25.5	23.3	9.0	17.0	11.1	7.5	7.5	4.8	3.1	4.6	6.0	6.0	41.1	4.2	3.4	2.7	3.4	6.1

Marketable Securities Current

us-gaap:MarketableSecuritiesCurrent

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
Value	487	474	497	479	495	472	318	268	236	220	210	207	196	177	141	115	89	83	84	83
Percentage of MarketableSecuritiesCurrent	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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	75.5	73.5	74.6	71.5	72.2	69.0	45.7	46.5	40.4	37.2	34.4	53.2	49.3	42.6	33.8	27.0	27.8	24.9	43.4	40.5

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

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	14	12	11	9.534	8.925	6.825	21	4.349	10	137	10	2.462	1.283	1.098	1.142	0.831	14	6.938	8.616	3.089	150	0.649	0.044	0.408	0.454	0.411	2.966	0.02	0.06	0.511	0.059
Percentage of AccountsReceivableNetCurrent	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	2.1	1.8	1.6	1.5	1.4	1.0	3.2	0.6	1.5	19.8	1.8	0.4	0.2	0.2	0.3	0.2	3.6	1.7	2.0	1.0	45.0	0.3	0.0	0.2	0.3	0.2	4.4	0.0	0.1	0.6	0.1

us-gaap:AccountsReceivableNetCurrent us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

xncr:MorphoSys, us-gaap:Royalty, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31
Value	1.5	1.4
Percentage of AccountsReceivableNetCurrent	10.1	11.2
Percentage of Assets	0.2	0.2
Percentage of Assets xncr:MorphoSys us-gaap:Royalty xncr:CollaborationAndLicenseAgreement	0.0	0.0

us-gaap:AccountsReceivableNetCurrent us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:AlexionPharmaceuticalsInc, xncr:OptionAndLicenseAgreement

Period End	2021-06-30	2021-03-31
Value	10	9.5
Percentage of AccountsReceivableNetCurrent	68.8	75.8
Percentage of Assets	1.5	1.4
Percentage of Assets xncr:AlexionPharmaceuticalsInc xncr:OptionAndLicenseAgreement	0.0	0.0

Prepaid Expense And Other Assets Current

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

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	15	14	10	10	7.398	6.476	6.547	7.533	11	9.433	10	12	12	6.649	5.606	7.027	7.617	4.365	2.901	3.448	2.192	1.843	1.201	0.865	0.711	0.422	0.134	0.162	0.402	0.159	0.06
Percentage of PrepaidExpenseAndOtherAssetsCurrent	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	2.2	2.0	1.5	1.6	1.1	1.0	1.0	1.1	1.7	1.4	1.8	2.1	2.0	1.1	1.4	1.8	1.8	1.0	0.7	1.1	0.7	1.0	0.6	0.4	0.4	0.2	0.2	0.2	0.5	0.2	0.1

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

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	38	28	21	15	10	9.194	7.453	6.684
Percentage of PropertyPlantAndEquipmentGross	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	5.5	4.2	3.7	3.9	2.5	4.4	11.0	7.7

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures

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	0.527	0.492	0.173	0.152	0.125	0.102	0.097	0.089
Percentage of PropertyPlantAndEquipmentGross	1.4	1.7	0.8	1.0	1.2	1.1	1.3	1.3
Percentage of Assets	0.1	0.1	0.0	0.0	0.0	0.0	0.1	0.1
Percentage of Assets us-gaap:FurnitureAndFixtures	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:LeaseholdsAndLeaseholdImprovements

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	6.957	6.831	4.774	4.01	3.79	3.754	3.086	3.081
Percentage of PropertyPlantAndEquipmentGross	18.0	24.0	22.5	26.7	35.6	40.8	41.4	46.1
Percentage of Assets	1.0	1.0	0.8	1.0	0.9	1.8	4.6	3.5
Percentage of Assets us-gaap:LeaseholdsAndLeaseholdImprovements	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

xncr:ComputersSoftwareAndEquipment

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	31	21	16	10	6.735	5.338	4.27	3.514
Percentage of PropertyPlantAndEquipmentGross	80.7	74.2	76.7	72.3	63.2	58.1	57.3	52.6
Percentage of Assets	4.4	3.1	2.8	2.8	1.6	2.6	6.3	4.0
Percentage of Assets xncr:ComputersSoftwareAndEquipment	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31	2014-12-31	2014-09-30	2014-06-30	2014-03-31	2013-12-31
Value	17	12	9.426	7.948	7.545	6.884	6.696	6.575	6.653	6.554	6.489	6.438	6.41	6.377
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	2.4	1.9	1.6	2.0	1.8	3.3	3.2	3.8	3.7	9.7	9.2	8.4	7.8	7.3

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

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	23	22	21	19	16	16	15	13	12	11	11	9.688	9.401	8.921	7.088	6.085	3.861	3.36	3.105	3.05	2.508	2.51	2.31	2.293	1.804	1.375	0.899	0.744	0.571	0.34	0.307
Percentage of PropertyPlantAndEquipmentNet	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	3.3	3.2	3.1	3.1	2.5	2.5	2.4	2.0	1.8	1.6	2.0	1.7	1.6	1.5	1.8	1.5	0.9	0.8	0.7	0.9	0.8	1.3	1.1	1.1	1.0	0.8	1.3	1.0	0.7	0.4	0.4

Indefinite Lived Intangible Assets Excluding Goodwill

us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass

us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill

us-gaap:Trademarks

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	399000.0	399000.0	399000.0	399000.0	399000.0	399000.0	400000.0	369000.0
Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill	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	0.2	0.6	0.4
Percentage of Assets us-gaap:Trademarks	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

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	16	15	15	15	15	14	14	14	13	12	11	11	11	11	11	11	10	10	10	10	10	10	9.971	9.617	9.691	9.509	9.116	8.957	9.058	8.899	8.814
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	2.4	2.2	2.3	2.4	2.4	2.2	2.2	2.0	2.0	1.8	2.1	2.0	1.9	1.8	2.9	2.8	2.6	2.6	2.4	3.3	3.1	5.2	4.8	4.5	5.6	5.3	13.4	12.6	11.9	10.8	10.1

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet

Period End	2020-12-31
Value	7146000.0
Percentage of FiniteLivedIntangibleAssetsNet	100.0
Percentage of Assets	1.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

Period End	2020-12-31	2019-12-31
Value	10	9.38
Percentage of OperatingLeaseRightOfUseAsset	100.0	100.0
Percentage of Assets	1.5	1.4

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

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	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	4.354	10	0.212	8.608	8.788	9.188	0.311	10	10	11	0.311	0.311	0.265	0.265	0.265	0.265	0.214	0.103	0.103	0.063	79	101	32	9.175	9.017	9.116	8.949	8.914
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
Percentage of Assets	0.6	1.5	0.0	1.3	1.4	1.4	0.0	1.5	1.6	1.6	0.1	0.1	0.0	0.0	0.1	0.1	0.1	0.0	0.0	0.0	37.5	58.6	18.0	13.5	12.7	11.9	10.8	10.2

Equity Securities Fv Ni

us-gaap:EquitySecuritiesFvNi

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	45	6.136	5.303	5.382	2.611	2.253
Percentage of EquitySecuritiesFvNi	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	6.5	0.9	0.8	0.8	0.4	0.3

us-gaap:EquitySecuritiesFvNi us-gaap:CounterpartyName, us-gaap:StatementClassOfStock

xncr:CatabasisPharmaceuticalsInc, us-gaap:CommonStock

Period End	2021-06-30
Value	8.102
Percentage of EquitySecuritiesFvNi	17.9
Percentage of Assets	1.2
Percentage of Assets xncr:CatabasisPharmaceuticalsInc us-gaap:CommonStock	0.0

xncr:InmuneBioInc, us-gaap:CommonStock

Period End	2021-06-30
Value	31
Percentage of EquitySecuritiesFvNi	69.0
Percentage of Assets	4.5
Percentage of Assets xncr:InmuneBioInc us-gaap:CommonStock	0.0

xncr:MiragenViridian, us-gaap:CommonStock

Period End	2021-06-30	2020-12-31
Value	5.897	5.303
Percentage of EquitySecuritiesFvNi	13.0	100.0
Percentage of Assets	0.8	0.8
Percentage of Assets xncr:MiragenViridian us-gaap:CommonStock	0.0	0.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel1

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	45	6.136	5.303	5.382	2.611	2.253
Percentage of EquitySecuritiesFvNi	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	6.5	0.9	0.8	0.8	0.4	0.3
Percentage of Assets us-gaap:FairValueInputsLevel1	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31
Value	5.303
Percentage of EquitySecuritiesFvNi	100.0
Percentage of Assets	0.8
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring	0.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31
Value	5.303
Percentage of EquitySecuritiesFvNi	100.0
Percentage of Assets	0.8
Percentage of Assets us-gaap:FairValueMeasurementsRecurring	0.0

us-gaap:EquitySecuritiesFvNi us-gaap:StatementClassOfStock

us-gaap:CommonStock

Period End	2021-06-30	2020-12-31
Value	45	5.303
Percentage of EquitySecuritiesFvNi	100.0	100.0
Percentage of Assets	6.5	0.8
Percentage of Assets us-gaap:CommonStock	0.0	0.0

Accounts Payable Current

us-gaap:AccountsPayableCurrent

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	7.112	7.663	8.954	13	10	10	10	8.304	8.994	5.485	3.797	5.983	4.916	8.523	6.869	6.602	7.379	4.275	3.88	7.334	7.694	4.291	6.4	5.107	3.077	2.556	1.691	2.098	1.374	2.104	2.633
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	1.0	1.1	1.3	2.0	1.6	1.5	1.5	1.2	1.3	0.8	0.7	1.0	0.8	1.4	1.8	1.7	1.8	1.0	0.9	2.3	2.3	2.2	3.1	2.4	1.8	1.4	2.5	3.0	1.8	2.6	3.0

Accrued Liabilities Current

us-gaap:AccruedLiabilitiesCurrent

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	17	12	17	11	9.157	7.292	8.995	7.832	6.226	5.705	9.662	5.671	5.923	4.611	5.48	4.636	3.984	6.502	6.692	6.536	3.278	2.391	3.634	3.817	2.537	1.686	2.251	1.764	1.331	1.465	1.393
Percentage of AccruedLiabilitiesCurrent	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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	1.8	2.5	1.8	1.4	1.1	1.3	1.1	0.9	0.8	1.7	1.0	1.0	0.8	1.4	1.2	1.0	1.6	1.6	2.0	1.0	1.2	1.8	1.8	1.5	0.9	3.3	2.5	1.7	1.8	1.6

Contract With Customer Liability Current

us-gaap:ContractWithCustomerLiabilityCurrent

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	19	77	92	43	44	46	45	45	45	59	40	40	60	60	60
Percentage of ContractWithCustomerLiabilityCurrent	100.0	100.0	100.0	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	2.8	11.2	13.2	6.8	6.9	6.9	6.7	6.6	6.6	8.5	6.9	6.8	10.2	9.8	15.4

Liabilities Current

us-gaap:LiabilitiesCurrent

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	45	99	121	70	66	65	66	64	63	73	53	52	71	73	101	100	107	106	106	110	115	34	43	56	8.408	6.877	6.196	9.93	5.946	6.827	7.479
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	6.6	14.4	17.2	10.9	10.3	9.9	9.9	9.4	9.3	10.5	9.3	8.9	12.0	12.0	26.0	25.2	25.8	25.5	24.8	34.4	34.7	17.7	21.0	26.8	4.9	3.8	9.1	14.0	7.8	8.3	8.6

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent

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	2322000.0	1934000.0	1889000.0	2158000.0	2094000.0	2136000.0	2169000.0	2197000.0	2214000.0	1987000.0
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	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

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	2.702	9.194	9.739	7.378	7.626	8.041	8.565	9.082	9.65	10
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	0.4	1.3	1.4	1.1	1.2	1.2	1.3	1.3	1.4	1.5

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	707000.0	1415000.0	2269000.0	2269000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	100.0	100.0	100.0	100.0
Percentage of Assets	0.1	0.2	0.3	0.4

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	729000.0	1436000.0	1415000.0	1415000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree	100.0	100.0	100.0	100.0
Percentage of Assets	0.1	0.2	0.2	0.2

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	688000.0	1396000.0	1436000.0	1436000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour	100.0	100.0	100.0	100.0
Percentage of Assets	0.1	0.2	0.2	0.2

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

Period End	2021-03-31	2020-12-31	2020-09-30
Value	1480000.0	1396000.0	1330000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive	100.0	100.0	100.0
Percentage of Assets	0.2	0.2	0.2

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

Period End	2021-03-31	2020-12-31	2020-09-30
Value	3861000.0	5342000.0	1238000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	100.0	100.0	100.0
Percentage of Assets	0.6	0.8	0.2

Operating Lease Liability

us-gaap:OperatingLeaseLiability

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	5.024	11	11	9.536	9.72	10	10	11	11	12
Percentage of OperatingLeaseLiability	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	1.6	1.7	1.5	1.5	1.5	1.6	1.6	1.7	1.8

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	5.334	13	14	10
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue	100.0	100.0	100.0	100.0
Percentage of Assets	0.8	2.0	2.0	1.7

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	310000.0	2502000.0	2659000.0	1454000.0
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	100.0	100.0	100.0	100.0
Percentage of Assets	0.0	0.4	0.4	0.2

Stockholders Equity

us-gaap:StockholdersEquity

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	2011-12-31
Value	646	583	572	568	570	593	593	610	608	609	521	532	519	537	282	290	301	303	313	202	208	158	162	153	162	169	59	59	65	70	73	-166.268	-157.703
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	100.0
Percentage of Assets	93.0	84.2	81.4	88.0	88.5	88.9	88.5	88.9	88.8	87.5	90.5	90.9	87.8	87.8	72.3	73.0	72.4	72.6	73.3	62.8	62.4	81.9	78.5	72.5	93.9	94.8	87.4	84.3	85.8	84.9	84.2	0.0	0.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome

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
Value	-0.015	0.097	0.074	0.567	1.483	1.056	1.161	1.436	1.629	0.345	-0.971	-2.338	-2.008	-2.201	-1.808	-1.097	-1.24	-1.196	-1.441	-0.25	0.216	0.103	-0.516	-0.006	-0.09	-0.035
Percentage of StockholdersEquity	-0.0	0.0	0.0	0.1	0.3	0.2	0.2	0.2	0.3	0.1	-0.2	-0.4	-0.4	-0.4	-0.6	-0.4	-0.4	-0.4	-0.5	-0.1	0.1	0.1	-0.3	-0.0	-0.1	-0.0
Percentage of Assets	-0.0	0.0	0.0	0.1	0.2	0.2	0.2	0.2	0.2	0.0	-0.2	-0.4	-0.3	-0.4	-0.5	-0.3	-0.3	-0.3	-0.3	-0.1	0.1	0.1	-0.2	-0.0	-0.1	-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

us-gaap:AdditionalPaidInCapital

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	2013-12-31	2012-12-31	2011-12-31
Value	962	951	937	919	908	895	887	877	865	851	845	839	828	821	570	566	562	557	552	431	428	426	424	422	421	419	302	300	1.043	1.014
Percentage of StockholdersEquity	148.8	163.0	163.8	161.7	159.1	151.1	149.7	143.8	142.3	139.8	162.0	157.6	159.6	152.8	202.3	195.0	186.5	183.5	176.1	213.0	205.6	268.4	261.1	275.4	259.8	247.7	511.0	409.1	-0.6	-0.6
Percentage of Assets	138.3	137.3	133.3	142.2	140.8	134.3	132.5	127.9	126.3	122.2	146.6	143.3	140.1	134.2	146.3	142.3	135.0	133.3	129.0	133.8	128.3	219.8	205.0	199.7	244.0	234.8	446.7	344.5	0.0	0.0
Percentage of Assets us-gaap:AdditionalPaidInCapital	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:CommonStock

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	2013-12-31	2012-12-31	2011-12-31
Value	0.584	0.583	0.58	0.573	0.572	0.57	0.569	0.567	0.565	0.564	0.563	0.562	0.558	0.556	0.47	0.47	0.468	0.467	0.466	0.411	0.409	0.407	0.405	0.405	0.405	0.404	0.314	0.314	0.001	0.001
Percentage of StockholdersEquity	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.1	0.2	0.2	0.3	0.2	0.3	0.2	0.2	0.5	0.4	-0.0	-0.0
Percentage of Assets	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.2	0.5	0.4	0.0	0.0
Percentage of Assets us-gaap:CommonStock	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:RetainedEarnings

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	2013-12-31	2012-12-31	2011-12-31
Value	-315.974	-368.222	-365.735	-352.044	-339.494	-304.476	-296.402	-269.49	-259.266	-243.232	-323.277	-305.078	-308.229	-282.361	-287.286	-275.443	-259.88	-252.996	-237.96	-228.895	-220.818	-267.983	-261.585	-269.342	-259.305	-250.437	-243.993	-227.571	-167.312	-158.718
Percentage of StockholdersEquity	-48.8	-63.1	-63.9	-61.9	-59.5	-51.3	-50.0	-44.2	-42.6	-39.9	-62.0	-57.3	-59.4	-52.5	-101.9	-94.8	-86.2	-83.3	-75.8	-113.1	-105.9	-168.7	-161.0	-175.7	-160.0	-147.9	-411.5	-309.5	100.6	100.6
Percentage of Assets	-45.4	-53.2	-52.0	-54.5	-52.7	-45.7	-44.2	-39.3	-37.9	-34.9	-56.1	-52.1	-52.1	-46.1	-73.6	-69.2	-62.4	-60.5	-55.5	-71.1	-66.1	-138.2	-126.4	-127.4	-150.3	-140.2	-359.7	-260.6	0.0	0.0
Percentage of Assets us-gaap:RetainedEarnings	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Common Stock Value

us-gaap:CommonStockValue

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	584000.0	583000.0	580000.0	573000.0	572000.0	570000.0	569000.0	567000.0	565000.0	564000.0	563000.0	562000.0	558000.0	556000.0	470000.0	470000.0	468000.0	467000.0	466000.0	411000.0	409000.0	407000.0	405000.0	405000.0	405000.0	404000.0	314000.0	314000.0	314000.0	314000.0	314000.0
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	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.2	0.2	0.5	0.4	0.4	0.4	0.4

Additional Paid In Capital

us-gaap:AdditionalPaidInCapital

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	962	951	937	919	908	895	887	877	865	851	845	839	828	821	570	566	562	557	552	431	428	426	424	422	421	419	302	302	301	301	300
Percentage of AdditionalPaidInCapital	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	138.3	137.3	133.3	142.2	140.8	134.3	132.5	127.9	126.3	122.2	146.6	143.3	140.1	134.2	146.3	142.3	135.0	133.3	129.0	133.8	128.3	219.8	205.0	199.7	244.0	234.8	446.7	426.2	394.9	365.0	344.5

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

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	-315.974	-368.222	-365.735	-352.044	-339.494	-304.476	-296.402	-269.49	-259.266	-243.232	-323.277	-305.078	-308.229	-282.361	-287.286	-275.443	-259.88	-252.996	-237.96	-228.895	-220.818	-267.983	-261.585	-269.342	-259.305	-250.437	-243.993	-242.644	-236.366	-231.322	-227.571
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	-45.4	-53.2	-52.0	-54.5	-52.7	-45.7	-44.2	-39.3	-37.9	-34.9	-56.1	-52.1	-52.1	-46.1	-73.6	-69.2	-62.4	-60.5	-55.5	-71.1	-66.1	-138.2	-126.4	-127.4	-150.3	-140.2	-359.7	-342.4	-309.5	-280.4	-260.6

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

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
Value	-15000.0	97000.0	74000.0	567000.0	1483000.0	1056000.0	1161000.0	1436000.0	1629000.0	345000.0	-971000.0	-2338000.0	-2008000.0	-2201000.0	-1808000.0	-1097000.0	-1240000.0	-1196000.0	-1441000.0	-250000.0	216000.0	103000.0	-516000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of Assets	-0.0	0.0	0.0	0.1	0.2	0.2	0.2	0.2	0.2	0.0	-0.2	-0.4	-0.3	-0.4	-0.5	-0.3	-0.3	-0.3	-0.3	-0.1	0.1	0.1	-0.2

Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31
Value	9.35	8.293	8.318	8.231	6.512	9.514	9.303	5.856	5.075	6.12	4.882	4.471	3.44	3.604	3.449	3.158	1.99	1.865	2.033	1.96	1.483	1.086	1.193	1.107
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31
Value	9.35	8.293	8.318	8.231	6.512	9.514	9.303	5.856	5.075	6.12	4.882	4.471	3.44	3.604	3.449	3.158	1.99	1.865	2.033	1.96	1.483	1.086	1.193	1.107
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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
Percentage of Assets us-gaap:AdditionalPaidInCapital	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

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
Value	-9.654	-29.966	17	-3.866	-27.682	9.46	-19.577	-6.477	109	-18.728	-16.781	-10.311	-28.419	-24.245	-6.666	-3.509	-12.962	-10.546	-15.788	134
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-14.3	-88.2	40.8	-10.9	-211.5	29.2	-556.8	-29.8	560.2	-16.7	-145.1	-35.5	0.0	0.0	-22.1	0.0	-103.7	-301.3	0.0	0.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

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
Value	-53.309	38	78	-50.56	59	12	15	22	-102.43	13	6.866	5.862	-190.169	12	8.939	4.933	9.525	8.553	-104.271	-127.665
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-79.0	112.0	188.2	-143.0	453.9	38.8	447.3	101.4	-525.7	12.2	59.4	20.2	0.0	0.0	29.6	0.0	76.2	244.4	0.0	0.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

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
Value	1.84	5.339	9.587	2.986	4.0	1.471	2.973	3.049	3.973	0.667	1.165	4.153	2.308	246	0.621	0.99	1.096	1.026	119	0.501
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.7	15.7	22.9	8.4	30.6	4.5	84.6	14.0	20.4	0.6	10.1	14.3	0.0	0.0	2.1	0.0	8.8	29.3	0.0	0.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

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	-61.123	13	105	-51.44	35	23	-0.877	18	10	-4.388	-8.75	-0.296	-216.28	235	2.894	2.414
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-90.6	39.5	251.9	-145.5	272.9	72.6	-24.9	85.6	54.9	-3.9	-75.7	-1.0	0.0	0.0	9.6	0.0

Depreciation Depletion And Amortization

us-gaap:DepreciationDepletionAndAmortization

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	1753000.0	1638000.0	1532000.0	1446000.0	1443000.0	1373000.0	1225000.0	1070000.0	1007000.0	996000.0	883000.0	816000.0	822000.0	730000.0	610000.0	556000.0	454000.0	410000.0	467000.0	371000.0	346000.0	282000.0	345000.0	274000.0	254000.0	240000.0	261000.0	135000.0	166000.0	320000.0	278000.0	134000.0	160000.0	139000.0
Percentage of DepreciationDepletionAndAmortization	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

Increase Decrease In Accounts Payable

us-gaap:IncreaseDecreaseInAccountsPayable

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	-551000.0	-1291000.0	-4155000.0	2596000.0	200000.0	124000.0	1884000.0	-689000.0	3508000.0	1689000.0	-2186000.0	1067000.0	-3607000.0	1654000.0	267000.0	-778000.0	3105000.0	395000.0	-3454000.0	-360000.0	3403000.0	-2109000.0	1293000.0	2030000.0	688000.0	699000.0	-407000.0	723000.0	-730000.0	-529000.0	-727000.0	585000.0	-149000.0	1610000.0
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

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

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
Value	-9.654	-29.966	17	-3.866	-27.682	9.46	-19.577	-6.477	109	-18.728	-16.781	-10.311	-28.419	-24.245	-6.666	-3.509	-12.962	-10.546	-15.788	134
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-14.3	-88.2	40.8	-10.9	-211.5	29.2	-556.8	-29.8	560.2	-16.7	-145.1	-35.5	0.0	0.0	-22.1	0.0	-103.7	-301.3	0.0	0.0

Net Income Loss

us-gaap:NetIncomeLoss

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	52	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.224	-16.034	80	-18.197	3.15	-25.869	-29.493	-11.843	-15.562	-6.885	-14.635	-9.065	-8.077	47	-6.398	7.757	-10.037	-8.868	-6.444	-1.349	-6.278	-5.044	-3.751
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	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-32.7	-35.5	-267.5	-24.9	-765.4	-47.0	-82.3	71.5	-157.4	10.8	0.0	0.0	-39.3	0.0	-55.1	-418.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Profit Loss

us-gaap:ProfitLoss

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
Value	52	-2.487	-13.691	-12.55	-35.018	-8.074	-26.912	-10.225	-16.033	80	-18.199	3.151	-25.868	-29.493	-11.843	-15.563	-6.044	-15.475	-9.065	-8.077
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	100.0	100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	77.5	-7.3	-32.7	-35.5	-267.5	-24.9	-765.4	-47.0	-82.3	71.5	-157.4	10.9	0.0	0.0	-39.3	0.0	-48.4	-442.1	0.0	0.0

Share Based Compensation

us-gaap:ShareBasedCompensation

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	9.35	8.293	8.558	8.318	8.231	6.512	7.178	9.514	9.303	5.856	5.075	6.12	4.882	4.471	3.44	3.604	3.449	3.158	1.99	1.865	2.033	1.96	1.483	1.086	1.193	1.107	0.751	0.471	0.361	0.278	0.144	0.044	0.005	0.005
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	100.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensation us-gaap:AwardType

us-gaap:EmployeeStock

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	0.253	0.248	0.213	0.194
Percentage of ShareBasedCompensation	2.7	3.0	2.6	3.0

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	7.355	6.53	6.667	5.882
Percentage of ShareBasedCompensation	78.7	78.7	81.0	90.3

us-gaap:RestrictedStockUnitsRSU

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	1.742	1.515	1.351	0.436
Percentage of ShareBasedCompensation	18.6	18.3	16.4	6.7

us-gaap:ShareBasedCompensation us-gaap:IncomeStatementLocation

us-gaap:GeneralAndAdministrativeExpense

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	3.193	2.737	2.804	2.291
Percentage of ShareBasedCompensation	34.1	33.0	34.1	35.2

us-gaap:ResearchAndDevelopmentExpense

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	6.157	5.556	5.427	4.221
Percentage of ShareBasedCompensation	65.9	67.0	65.9	64.8

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

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
Value	-53.309	38	78	-50.56	59	12	15	22	-102.43	13	6.866	5.862	-190.169	12	8.939	4.933	9.525	8.553	-104.271	-127.665
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	-79.0	112.0	188.2	-143.0	453.9	38.8	447.3	101.4	-525.7	12.2	59.4	20.2	0.0	0.0	29.6	0.0	76.2	244.4	0.0	0.0

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

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	2.283	1.951	3.149	4.695	0.622	2.073	2.91	2.576	1.452	0.415	2.787	1.009	1.07	2.346	1.477	2.578	0.762	0.494	0.274	0.74	0.176	0.317	0.206	0.609	0.54	0.575	0.22	0.224	0.27	0.066	0.0	0.1	0.0	0.036
Percentage of PaymentsToAcquirePropertyPlantAndEquipment	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0	0.0	100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

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
Value	1.84	5.339	9.587	2.986	4.0	1.471	2.973	3.049	3.973	0.667	1.165	4.153	2.308	246	0.621	0.99	1.096	1.026	119	0.501
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
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax	2.7	15.7	22.9	8.4	30.6	4.5	84.6	14.0	20.4	0.6	10.1	14.3	0.0	0.0	2.1	0.0	8.8	29.3	0.0	0.0

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:EmployeeStockOption

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	8759400.0	8778200.0	7751800.0	8146900.0	8231000.0	8162200.0	7174300.0	7231100.0	7285000.0	7199000.0	5966900.0	5876700.0	6219200.0	6252000.0	5093400.0	5044200.0	5073000.0	4987300.0	4045800.0	4027900.0	4090100.0	4093700.0	3370900.0	3377900.0	3383700.0	3248200.0	2826800.0	2799500.0	2593500.0	2487700.0	1794200.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:EmployeeStockOption

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	28.97	28.82	26.23	25.66	25.52	25.19	24.03	23.63	23.2	22.81	19.71	19.29	18.36	17.69	15.32	15.23	15.02	14.43	11.95	11.12	10.3	9.74	8.5	8.47	8.41	7.88	5.12	5.06	4.61	4.34	1.66
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:EmployeeAndNonEmployeeStockOption

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31	2013-12-31	2012-12-31
Value	26.23	24.03	19.71	15.32	11.95	8.5	5.12	1.66	0.59
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

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	8955000.0	4318000.0	3298000.0	3051000.0	4044000.0	3892000.0	3587000.0	3454000.0
Percentage of DeferredTaxAssetsNet	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

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	105	77	82	67	69	76	59	84
Percentage of DeferredTaxAssetsValuationAllowance	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AccretionAmortizationOfDiscountsAndPremiumsInvestments

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
Value	-846000.0	-865000.0	-709000.0	143000.0	265000.0	573000.0	988000.0	1457000.0	1275000.0	601000.0	462000.0	338000.0	74000.0	-480000.0	-697000.0	-792000.0	-697000.0	-659000.0	-639000.0	-522000.0	-450000.0	-426000.0	-454000.0	-402000.0	-177000.0	-63000.0
Percentage of AccretionAmortizationOfDiscountsAndPremiumsInvestments	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

us-gaap:ContractWithCustomerLiabilityRevenueRecognized

xncr:AlexionPharmaceuticalsInc, us-gaap:Royalty, xncr:OptionAndLicenseAgreement

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
Value	5.2	5.3	4.3	3.8	3.3	2.5	1.4	1.1	0.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0

xncr:Genentech, xncr:ResearchActivity, xncr:CollaborationAndLicenseAgreement

Period End	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31
Value	0.9	0.8	0.7	0.6	0.7	0.6	0.3
Percentage of ContractWithCustomerLiabilityRevenueRecognized	20.9	21.1	21.2	24.0	50.0	54.5	0.0

xncr:Genentech, xncr:ResearchActivity, xncr:ResearchAndLicenseAgreement

Period End	2020-09-30
Value	0.8
Percentage of ContractWithCustomerLiabilityRevenueRecognized	18.6

xncr:MorphoSys, us-gaap:Royalty, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	1.2	1.4	1.3	0.2
Percentage of ContractWithCustomerLiabilityRevenueRecognized	23.1	26.4	0.0	4.7

xncr:MorphoSys, xncr:Milestone, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31	2020-06-30	2020-02-29	2020-03-31	2017-06-30
Value	0.0	12	0.0	12	12	12
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	235.8	0.0	378.8	0.0	0.0

xncr:Novartis, xncr:Milestone, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2019-09-30
Value	1.0	10.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	19.2	714.3

xncr:VirBiotechnology, us-gaap:Royalty, xncr:PatentLicenseAgreement

Period End	2021-06-30
Value	0.9
Percentage of ContractWithCustomerLiabilityRevenueRecognized	17.3

xncr:ZenasBioPharmaLimited, us-gaap:License, xncr:LicenseAgreement

Period End	2020-12-31
Value	16
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:Aimmune, xncr:LicenseDevelopmentAndCommercializationAgreement

Period End	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	0.0	0.0	0.0	9.6
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	0.0	0.0	290.9

xncr:AlexionPharmaceuticalsInc, xncr:OptionAndLicenseAgreement

Period End	2020-12-31	2020-09-30	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31
Value	14	4.3	2.5	5.4	4.0	0.0	11	9.0	0.0	0.0	0.0	0.0	0.0	0.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	100.0	100.0	385.7	363.6	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

xncr:Astellas, xncr:ResearchAndLicenseAgreement

Period End	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31
Value	0.0	0.7	0.3	0.2	0.0	13	0.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	18.4	9.1	8.0	0.0	1254.5	0.0

xncr:Genentech, xncr:CollaborationAndLicenseAgreement

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	0.2	1.2	0.9	0.8	0.7	0.7	0.7	0.6	112
Percentage of ContractWithCustomerLiabilityRevenueRecognized	44.2	3.8	0.0	20.9	21.1	21.2	28.0	50.0	54.5	0.0

xncr:Gilead, xncr:LicenseAgreement

Period End	2020-09-30	2020-06-30	2020-04-30	2020-03-31
Value	0.0	7.5	7.5	6.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	197.4	0.0	181.8

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31
Value	16	14
Percentage of ContractWithCustomerLiabilityRevenueRecognized	311.5	275.5

xncr:MorphoSys, xncr:CollaborationAndLicenseAgreement

Period End	2020-09-30	2020-07-31	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2018-06-30	2018-03-31
Value	25	25	0.0	12	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Percentage of ContractWithCustomerLiabilityRevenueRecognized	581.4	0.0	0.0	378.8	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

xncr:VirBiotechnology, xncr:ResearchAndLicenseAgreement

Period End	2020-09-30	2020-06-30	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31
Value	0.0	0.3	0.002019	0.1	0.7	0.0	0.002019
Percentage of ContractWithCustomerLiabilityRevenueRecognized	0.0	7.9	0.1	4.0	50.0	0.0	0.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedGainLoss

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	-113000.0	23000.0	-493000.0	-916000.0	427000.0	-105000.0	-275000.0	-193000.0	1284000.0	1316000.0	1367000.0	-330000.0	193000.0	-393000.0	-711000.0
Percentage of DebtSecuritiesAvailableForSaleUnrealizedGainLoss	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:EquitySecuritiesFvNiGainLoss

Period End	2021-06-30	2021-03-31	2020-06-30	2020-03-31
Value	43	12	0.358	-2.336
Percentage of EquitySecuritiesFvNiGainLoss	100.0	100.0	100.0	100.0

us-gaap:EquitySecuritiesFvNiRealizedGainLoss

Period End	2021-06-30	2021-03-31
Value	18	0.001
Percentage of EquitySecuritiesFvNiRealizedGainLoss	100.0	100.0

us-gaap:EquitySecuritiesFvNiRealizedGainLoss us-gaap:CounterpartyName, us-gaap:SubsequentEventType

xncr:Aimmune, us-gaap:SubsequentEvent

Period End	2020-10-31
Value	5.4
Percentage of EquitySecuritiesFvNiRealizedGainLoss	0.0

us-gaap:EquitySecuritiesFvNiRealizedGainLoss us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:InmuneBioInc, xncr:LicenseAgreement

Period End	2021-06-30
Value	18
Percentage of EquitySecuritiesFvNiRealizedGainLoss	100.0

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	24	12	-1.49	2.8	0.3	-2.336
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss us-gaap:CounterpartyName, us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement

xncr:InmuneBioInc, us-gaap:OtherIncome, xncr:LicenseAgreement

Period End	2021-06-30
Value	27
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss	112.5

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CatabasisPharmaceuticalsInc, xncr:TechnologyLicenseAgreement

Period End	2021-06-30
Value	-3.7
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss	-15.0

xncr:InmuneBioInc, xncr:LicenseAgreement

Period End	2021-06-30
Value	27
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss	112.9

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement

Period End	2021-06-30
Value	0.5
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss	2.0

us-gaap:GainLossOnDispositionOfAssets1

Period End	2020-12-31	2020-09-30	2019-12-31	2019-09-30	2018-12-31	2017-12-31	2015-12-31	2015-09-30	2014-12-31	2014-09-30	2013-12-31	2013-09-30
Value	0	1000.0	0	-3000.0	8000.0	-85000.0	0	0	1000.0	0	0	4000.0
Percentage of GainLossOnDispositionOfAssets1	0.0	100.0	0.0	100.0	100.0	100.0	0.0	0.0	100.0	0.0	0.0	100.0

us-gaap:IncomeLossFromEquityMethodInvestments

Period End	2020-12-31	2020-09-30	2020-06-30	2020-03-31
Value	22	0.0	0.0	4.589
Percentage of IncomeLossFromEquityMethodInvestments	100.0	0.0	0.0	100.0

us-gaap:IncreaseDecreaseInAccountsAndOtherReceivables

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	2.3	1.082	1.909	0.609	2.1	-14.749	17	-5.781	-127.611	127	7.725	1.18	0.184	-0.044	0.311	-14.045	7.938	-1.678	5.528	-147.266	149	0.604
Percentage of IncreaseDecreaseInAccountsAndOtherReceivables	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable

Period End	2020-09-30	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
Value	804000.0	-400000.0	704000.0	900000.0	-1000.0	1000.0	0	-157000.0	156000.0	-455000.0	280000.0	110000.0	-335000.0	-1381000.0
Percentage of IncreaseDecreaseInAccruedIncomeTaxesPayable	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

us-gaap:IncreaseDecreaseInAccruedInvestmentIncomeReceivable

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
Value	-185000.0	-311000.0	-55000.0	-221000.0	-699000.0	-215000.0	384000.0	-151000.0	185000.0	-31000.0	-89000.0	29000.0	286000.0	309000.0	-295000.0	444000.0	-335000.0	479000.0	-11000.0	701000.0	-119000.0	-41000.0	239000.0	-11000.0	524000.0	146000.0
Percentage of IncreaseDecreaseInAccruedInvestmentIncomeReceivable	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:IncreaseDecreaseInAccruedLiabilities

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	4815000.0	-5090000.0	6222000.0	2224000.0	1865000.0	-1703000.0	1163000.0	1606000.0	521000.0	-3957000.0	3990000.0	-251000.0	1312000.0	-869000.0	844000.0	652000.0	-2518000.0	-190000.0	156000.0	3259000.0	886000.0	-1243000.0	-183000.0	1280000.0	851000.0	-523000.0	487000.0	434000.0	-134000.0	72000.0	606000.0	-28000.0	96000.0	-565000.0
Percentage of IncreaseDecreaseInAccruedLiabilities	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:IncreaseDecreaseInContractWithCustomerAsset

Period End	2021-06-30	2021-03-31	2020-12-31
Value	-12.0	0.062	12
Percentage of IncreaseDecreaseInContractWithCustomerAsset	100.0	100.0	100.0

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

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	-58.621	-14.794	48	-0.845	-1.491	-0.955	-1.061	-0.586	-14.362	23	0.0	-20.05
Percentage of IncreaseDecreaseInContractWithCustomerLiability	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

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	1430000.0	3438000.0	541000.0	2786000.0	914000.0	-71000.0	-985000.0	-3775000.0	1874000.0	-942000.0	-1766000.0	67000.0	5425000.0	1043000.0	-1266000.0	-756000.0	3262000.0	1465000.0	-588000.0	1257000.0	348000.0	683000.0	353000.0	181000.0	392000.0	142000.0	11000.0	-238000.0	201000.0	99000.0	-1096000.0	912000.0
Percentage of IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:LeaseCost

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	632000.0	624000.0	628000.0	669000.0	686000.0	670000.0	661000.0	659000.0	697000.0
Percentage of LeaseCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments

Period End	2020-12-31	2020-09-30	2016-12-31	2015-12-31
Value	0	0	-1000.0	1000.0
Percentage of MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments	0.0	0.0	100.0	100.0

us-gaap:MarketableSecuritiesUnrealizedGainLoss

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
Value	-112000.0	23000.0	-493000.0	-916000.0	427000.0	-105000.0	-275000.0	-193000.0	1284000.0	1316000.0	1367000.0	-330000.0	193000.0	-393000.0	-711000.0	143000.0	-44000.0	245000.0	-1191000.0	-466000.0	113000.0	619000.0	-510000.0	84000.0	-55000.0	-35000.0
Percentage of MarketableSecuritiesUnrealizedGainLoss	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:NoncashProjectAbandonmentCosts

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	117000.0	193000.0	132000.0	236000.0	139000.0	28000.0	106000.0	25000.0	32000.0	58000.0	121000.0	68000.0	45000.0	5000.0	123000.0	48000.0	216000.0	9000.0	249000.0	62000.0	36000.0	9000.0	16000.0	226000.0	17000.0	37000.0	13000.0	365000.0	121000.0	10000.0	-36000.0	65000.0	8000.0	168000.0
Percentage of NoncashProjectAbandonmentCosts	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:OperatingLeaseCost

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	614000.0	614000.0	607000.0	599000.0	648000.0	700000.0	648000.0	648000.0	650000.0	700000.0
Percentage of OperatingLeaseCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:OperatingLeasePayments

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	548000.0	499000.0	583000.0	527000.0	566000.0	700000.0	544000.0	531000.0	344000.0	700000.0
Percentage of OperatingLeasePayments	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:PaymentsToAcquireIntangibleAssets

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	1252000.0	72000.0	1086000.0	676000.0	929000.0	538000.0	753000.0	768000.0	1113000.0	1051000.0	633000.0	420000.0	493000.0	389000.0	447000.0	428000.0	390000.0	702000.0	295000.0	446000.0	418000.0	343000.0	525000.0	305000.0	344000.0	571000.0	368000.0	349000.0	406000.0	382000.0	11000.0	288000.0	338000.0	521000.0
Percentage of PaymentsToAcquireIntangibleAssets	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:PaymentsToAcquireMarketableSecurities

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
Value	147	84	166	174	159	142	144	107	194	49	46	45	254	31	27	15	26	6.988	114	195	-9.217	16	47	20	100	47
Percentage of PaymentsToAcquireMarketableSecurities	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions

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	2014-03-31
Value	0.903	5.339	8.885	2.986	3.275	1.471	2.314	3.049	3.239	0.667	0.549	4.153	1.805	1.11	0.128	0.989	0.654	1.026	0.212	0.501	0.247	0.2	0.011	0.114	0.249	0.18	0.001	0.004
Percentage of ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities

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
Value	97	124	249	129	220	157	164	133	94	64	56	52	65	47	38	23	36	16	10	68	0.0	26	6.35
Percentage of ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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

us-gaap:ProceedsFromStockPlans

Period End	2020-12-31	2020-09-30	2019-12-31	2019-09-30	2018-12-31	2018-09-30	2017-12-31	2017-09-30	2016-12-31	2016-09-30	2015-12-31	2015-09-30	2014-12-31
Value	702000.0	0	659000.0	0	616000.0	0	493000.0	1000.0	319000.0	0	376000.0	0	177000.0
Percentage of ProceedsFromStockPlans	100.0	0.0	100.0	0.0	100.0	0.0	100.0	100.0	100.0	0.0	100.0	0.0	100.0

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

Period End	2020-12-31	2020-09-30	2020-06-30
Value	2700000.0	300000.0	100000.0
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue

us-gaap:RestrictedStockUnitsRSU

Period End	2021-06-30	2021-03-31	2020-12-31
Value	3.8	32.36	-0.13
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

us-gaap:RestrictedStockUnitsRSU

Period End	2021-06-30	2021-03-31	2020-12-31
Value	-0.26	43.11	0.59
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue

us-gaap:RestrictedStockUnitsRSU

Period End	2021-06-30	2021-03-31	2020-12-31
Value	-0.04	31.75	1.03
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate

us-gaap:EmployeeStockOption

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	2018-09-30	2018-06-30	2018-03-31	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
Value	55.3	55.6	56.2	0.561	0.539	0.608	0.613	0.613	0.728	0.729	0.731	0.967	0.889	0.892	0.793	0.761	0.758	0.865	0.756	0.766	0	0.774	0.752	0.752	0.299	0.568
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum

us-gaap:EmployeeStock

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	2017-06-30	2016-12-31	2016-09-30	2016-06-30
Value	66.4	66.4	3.77	62.6	0.626	-0.0003	0.714	0.714	0	0.714	0.714	0	0.798	0.798	0.002	0.796	0.796
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0	100.0	0.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum

us-gaap:EmployeeStock

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	2017-06-30	2016-12-31	2016-09-30	2016-06-30
Value	46.1	50.8	-0.03	50.8	0.508	-0.0423	0.55	0.55	-0.042	0.612	0.612	0	0.678	0.678	0	0.678	0.678
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0	100.0	0.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate

us-gaap:EmployeeStockOption

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	2018-09-30	2018-06-30	2018-03-31	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	2014-09-30	2014-06-30	2014-03-31	2013-09-30	2013-03-31
Value	1.03	1.02	0.35	0.0041	0.0171	0.0152	0.0207	0.0253	0.0287	0.0277	0.025	0.0195	0.0191	0.0207	0.0123	0.0136	0.0156	0.0195	0.016	0.0161	0.0202	0.0193	0.0201	0.0196	0.0219
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum

us-gaap:EmployeeStock

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	1.65	1.65	0	1.65	0.0165	0.0165	0	0.027	0.027	0.027	0.0029	0.0241	0.0241	0.018	0.0071	0.0109	0.0109	0.0093	0	0.0093	0.0093	0.0093
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum	100.0	100.0	0.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum

us-gaap:EmployeeStock

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	0.04	0.09	-0.09	0.18	0.0018	0.0156	0	0.0147	0.0147	0.0147	0	0.0147	0.0147	0.0147	0	0.0047	0.0047	0.0055	0	0.0047	0.0047	0.0055
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum	100.0	100.0	100.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31
Value	132620.0	64824.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross

us-gaap:EmployeeStockOption

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	2018-09-30	2018-06-30	2018-03-31	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	2014-09-30	2014-06-30	2014-03-31	2013-09-30	2013-06-30	2013-03-31
Value	166660.0	1321900.0	129080.0	296280.0	1137400.0	219790.0	356140.0	1342400.0	126000.0	159750.0	1393600.0	82000.0	220500.0	1135600.0	137000.0	181000.0	957000.0	20500.0	189500.0	720250.0	1019000.0	110000.0	700500.0	0	0	0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

us-gaap:EmployeeStockOption

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	2018-09-30	2018-06-30	2018-03-31	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	2014-09-30	2014-06-30	2014-03-31
Value	-0.29	22.83	0.16	-0.2	16.64	-0.03	-0.46	21.2	0.71	0.74	16.12	-0.04	16.95	16.95	0.81	8.45	8.3	0.15	0.04	10.54	-0.24	-0.09	7.44
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31
Value	-1.12	23.14
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	100.0	100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31
Value	2.34	33.0
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	100.0	100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31
Value	-0.51	43.24
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	100.0	100.0

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised us-gaap:AwardType

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31
Value	52790.0	230700.0
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised	100.0	100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan

Period End	2021-06-30	2020-06-30	2019-06-30	2018-12-31	2018-09-30	2018-06-30	2017-12-31	2017-09-30	2016-12-31	2016-09-30	2015-12-31
Value	937000.0	725000.0	734000.0	616000.0	0	504000.0	493000.0	1000.0	319000.0	0	376000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	100.0	100.0	100.0	100.0	0.0	100.0	100.0	100.0	100.0	0.0	100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital

Period End	2021-06-30	2020-06-30	2019-06-30	2018-12-31	2018-09-30	2018-06-30	2017-12-31	2017-09-30	2016-12-31	2016-09-30	2015-12-31
Value	937000.0	725000.0	734000.0	615000.0	0	504000.0	493000.0	1000.0	318000.0	0	376000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	100.0	100.0	100.0	99.8	0.0	100.0	100.0	100.0	99.7	0.0	100.0

us-gaap:StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures

us-gaap:AdditionalPaidInCapital

Period End	2021-03-31
Value	-1000.0
Percentage of StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	100.0

us-gaap:CommonStock

Period End	2021-03-31
Value	1000.0
Percentage of StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31
Value	0.903	5.339	2.986	3.275	1.471	3.049	3.239	0.667	0.549	4.154	1.805	1.11	0.128	0.989	0.654	1.026	0.212	0.501	0.247	0.2	0.011	0.114	0.249	0.18
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31
Value	0.902	5.337	2.985	3.273	1.47	3.047	3.238	0.666	0.549	4.15	1.803	1.108	0.128	0.987	0.653	1.025	0.211	0.499	0.245	0.198	0.011	0.114	0.249	0.176
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation	99.9	100.0	100.0	99.9	99.9	99.9	100.0	99.9	100.0	99.9	99.9	99.8	100.0	99.8	99.8	99.9	99.5	99.6	99.2	99.0	100.0	100.0	100.0	97.8

us-gaap:CommonStock

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	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31	2015-09-30	2015-06-30	2015-03-31
Value	0.001	0.002	0.001	0.002	0.001	0.002	0.001	0.001	0.0	0.004	0.002	0.002	0.0	0.002	0.001	0.001	0.001	0.002	0.002	0.002	0.0	0.0	0.0	0.004
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation	0.1	0.0	0.0	0.1	0.1	0.1	0.0	0.1	0.0	0.1	0.1	0.2	0.0	0.2	0.2	0.1	0.5	0.4	0.8	1.0	0.0	0.0	0.0	2.2

us-gaap:VariableLeaseCost

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	18000.0	10000.0	21000.0	70000.0	38000.0	22000.0	13000.0	11000.0	47000.0
Percentage of VariableLeaseCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:CashConsiderationOnSaleOfOption us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CashConsiderationOnSaleOfOption

xncr:InmuneBioInc, xncr:LicenseAgreement

Period End	2021-06-30
Value	15
Percentage of CashConsiderationOnSaleOfOption	100.0

xncr:CollaborativeArrangementNonrefundableUpfrontFees us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CollaborativeArrangementNonrefundableUpfrontFees

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2020-11-30
Value	50
Percentage of CollaborativeArrangementNonrefundableUpfrontFees	100.0

xncr:OmerosCorporation, xncr:TechnologyLicenseAgreement

Period End	2020-08-31
Value	5.0
Percentage of CollaborativeArrangementNonrefundableUpfrontFees	0.0

xncr:CollaborativeArrangementPercentageEquityPrivateCompany us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CollaborativeArrangementPercentageEquityPrivateCompany

xncr:PrivateBiotechCompany, xncr:LicenseAgreement

Period End	2020-11-30
Value	15.0
Percentage of CollaborativeArrangementPercentageEquityPrivateCompany	100.0

xncr:ZenasBioPharmaLimited, xncr:LicenseAgreement

Period End	2020-11-30
Value	15.0
Percentage of CollaborativeArrangementPercentageEquityPrivateCompany	100.0

xncr:ConsiderationOnSaleOfOption us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:ConsiderationOnSaleOfOption

xncr:InmuneBioInc, xncr:LicenseAgreement

Period End	2021-06-30
Value	18
Percentage of ConsiderationOnSaleOfOption	100.0

xncr:ConsiderationOnSaleOfOptionEquityIssuedValue us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:ConsiderationOnSaleOfOptionEquityIssuedValue

xncr:InmuneBioInc, xncr:LicenseAgreement

Period End	2021-06-30
Value	3300000.0
Percentage of ConsiderationOnSaleOfOptionEquityIssuedValue	100.0

xncr:IncreaseDecreaseInLeaseLiabilitiesAndRightOfUseAssets

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	-41000.0	-42000.0	-157000.0	-58000.0	-56000.0	-54000.0	1464000.0	-45000.0	194000.0	-259000.0
Percentage of IncreaseDecreaseInLeaseLiabilitiesAndRightOfUseAssets	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationShareValue us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationShareValue

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement

Period End	2020-12-31
Value	6.0
Percentage of NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationShareValue	100.0

xncr:PrivateBiotechCompany, xncr:LicenseAgreement

Period End	2020-11-30
Value	16
Percentage of NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationShareValue	0.0

xncr:ZenasBioPharmaLimited, xncr:LicenseAgreement

Period End	2020-11-30
Value	16
Percentage of NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationShareValue	0.0

xncr:RentExpensePerSquareFoot us-gaap:StatementScenario, us-gaap:PropertyPlantAndEquipmentByType

xncr:RentExpensePerSquareFoot

srt:ScenarioForecast, xncr:PasadenaCaOfficeAndLaboratorySpace

Period End	2022-07-01
Value	4.65
Percentage of RentExpensePerSquareFoot	100.0

xncr:ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized us-gaap:PlanName

xncr:ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized

xncr:EquityIncentivePlan2013

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	2014-01-02
Value	0	4.0	0	3.96	0	0.04	0	0	0	0.04	0	0	0	0.04	0	0	0	0.04	0	0	0	0.04	0	0	0.04
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized	0.0	100.0	0.0	100.0	0.0	100.0	0.0	0.0	0.0	100.0	0.0	0.0	0.0	100.0	0.0	0.0	0.0	100.0	0.0	0.0	0.0	100.0	0.0	0.0	100.0

xncr:ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized us-gaap:Range, us-gaap:AwardType

srt:Maximum, us-gaap:EmployeeStock

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	0	1.0	0	0.99	0	0.01	0	0	0	0.01	0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized	0.0	25.0	0.0	25.0	0.0	25.0	0.0	0.0	0.0	25.0	0.0

xncr:TaxRefundReceived us-gaap:IncomeTaxAuthority

xncr:TaxRefundReceived

us-gaap:DomesticCountry

Period End	2020-09-30
Value	800000.0
Percentage of TaxRefundReceived	100.0

us-gaap:AssetsFairValueDisclosure

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	576	593	615	559	581	588	583	599	616	506	522	528	551	578	351	368	377	390	401	297	167	177	190	149
Percentage of AssetsFairValueDisclosure	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel1

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
Value	116	171	164	39	105	52	32	30	22	15	18	15	31	247	5.175	9.33	10	11	12	10	6.969	6.815	9.453	9.904	1.379	2.04
Percentage of AssetsFairValueDisclosure	20.3	28.9	26.7	7.1	18.2	8.9	5.5	5.1	3.7	3.1	3.5	3.0	5.6	42.8	1.5	2.5	2.7	2.8	3.0	3.6	4.2	3.8	5.0	6.6	0.0	0.0

us-gaap:FairValueInputsLevel2

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
Value	442	393	435	519	475	536	550	569	593	490	504	512	520	330	346	359	367	379	388	287	160	170	180	139	147	47
Percentage of AssetsFairValueDisclosure	76.7	66.4	70.7	92.9	81.8	91.1	94.5	94.9	96.3	96.9	96.5	97.0	94.4	57.2	98.5	97.5	97.3	97.2	97.0	96.4	95.8	96.2	95.0	93.4	0.0	0.0

us-gaap:FairValueInputsLevel3

Period End	2021-06-30	2021-03-31	2020-12-31
Value	17	28	16
Percentage of AssetsFairValueDisclosure	3.0	4.8	2.6

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	164	32	18	5.175	12	9.453	54
Percentage of AssetsFairValueDisclosure	26.7	5.5	3.5	1.5	3.0	5.0	0.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	435	550	504	346	388	180
Percentage of AssetsFairValueDisclosure	70.7	94.5	96.5	98.5	97.0	95.0

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31
Value	16
Percentage of AssetsFairValueDisclosure	2.6

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	615	583	522	351	401	190	54
Percentage of AssetsFairValueDisclosure	100.0	100.0	100.0	100.0	100.0	100.0	0.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

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	49000.0	119000.0	94000.0	581000.0	1496000.0	1656000.0	1201000.0	1455000.0	1686000.0	659000.0	188000.0	1000.0	21000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

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	13000.0	12000.0	57000.0	377000.0	786000.0	22000.0	195000.0	228000.0	219000.0	69000.0	1000.0	1000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	26.5	10.1	60.6	64.9	52.5	1.3	16.2	15.7	13.0	10.5	0.5	100.0

us-gaap:USTreasuryAndGovernment

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	2018-06-30
Value	36000.0	107000.0	37000.0	204000.0	710000.0	1634000.0	1006000.0	1227000.0	1467000.0	590000.0	187000.0	21000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	73.5	89.9	39.4	35.1	47.5	98.7	83.8	84.3	87.0	89.5	99.5	100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

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	54000.0	12000.0	9000.0	4000.0	3000.0	590000.0	30000.0	10000.0	47000.0	305000.0	1149000.0	2330000.0	2019000.0	2191000.0	1799000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

Period End	2021-06-30	2021-03-31	2020-12-31	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
Value	31000.0	5000.0	6000.0	590000.0	30000.0	10000.0	2000.0	71000.0	345000.0	471000.0	654000.0	830000.0	590000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	57.4	41.7	66.7	100.0	100.0	100.0	4.3	23.3	30.0	20.2	32.4	37.9	32.8

us-gaap:USTreasuryAndGovernment

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2020-06-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2018-06-30	2018-03-31	2017-12-31
Value	23000.0	7000.0	3000.0	4000.0	3000.0	45000.0	234000.0	804000.0	1859000.0	1365000.0	1361000.0	1209000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	42.6	58.3	33.3	100.0	100.0	95.7	76.7	70.0	79.8	67.6	62.1	67.2

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis

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	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	442	393	435	518	473	535	549	567	591	490	505	515	522	333	360	368	380	390	287	160	170	181
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

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	104	73	119	231	266	333	281	217	198	105	105	98	96	113	123
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis	23.7	18.8	27.5	44.6	56.3	62.3	51.2	38.3	33.5	21.5	20.8	19.1	18.5	34.1	0.0

us-gaap:USTreasuryAndGovernment

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	337	319	315	287	207	201	268	350	393	384	399	416	425	219	224
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis	76.3	81.2	72.5	55.4	43.7	37.7	48.8	61.7	66.5	78.5	79.2	80.9	81.5	65.9	0.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	153	25	1.03	31	163	191	238	274	197	77	86	97
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	153	25	1.03	31	163	190	237	273	197	77	86	96
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	288	368	434	487	196	177	141	115	89	83	84	83
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	288	368	434	487	196	177	141	115	89	83	84	83
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities

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	2017-09-30	2017-06-30	2017-03-31	2016-12-31	2016-09-30	2016-06-30	2016-03-31	2015-12-31
Value	442	393	435	519	475	536	550	569	593	490	504	512	520	330	359	367	379	388	287	160	170	180
Percentage of AvailableForSaleSecuritiesDebtSecurities	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:BalanceSheetLocation

xncr:MarketableSecurities

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	442	393	435	519	475	536	550	569	593	490	504	512	520	330	346
Percentage of AvailableForSaleSecuritiesDebtSecurities	100.0	100.0	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

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31
Value	119	281	104	123
Percentage of AvailableForSaleSecuritiesDebtSecurities	27.5	51.1	20.8	0.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasuryAndGovernment

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31
Value	315	269	399	223
Percentage of AvailableForSaleSecuritiesDebtSecurities	72.5	48.9	79.2	0.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel2, us-gaap:CorporateDebtSecurities

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	2017-12-31
Value	104	73	119	231	267	332	281	217	198	105	104	98	123
Percentage of AvailableForSaleSecuritiesDebtSecurities	23.7	18.8	27.5	44.6	56.3	62.1	51.1	38.2	33.4	21.5	20.8	19.1	0.0

us-gaap:FairValueInputsLevel2, us-gaap:USTreasuryAndGovernment

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	2017-12-31
Value	337	320	315	287	207	203	269	351	395	385	399	414	223
Percentage of AvailableForSaleSecuritiesDebtSecurities	76.3	81.2	72.5	55.4	43.7	37.9	48.9	61.8	66.6	78.5	79.2	80.9	0.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31
Value	119	281	104	123
Percentage of AvailableForSaleSecuritiesDebtSecurities	27.5	51.1	20.8	0.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasuryAndGovernment

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31
Value	315	269	399	223
Percentage of AvailableForSaleSecuritiesDebtSecurities	72.5	48.9	79.2	0.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

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	104	73	119	231	267	332	281	217	198	105	104	98	96	112	123
Percentage of AvailableForSaleSecuritiesDebtSecurities	23.7	18.8	27.5	44.6	56.3	62.1	51.1	38.2	33.4	21.5	20.8	19.1	18.5	34.0	0.0

us-gaap:USTreasuryAndGovernment

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	337	320	315	287	207	203	269	351	395	385	399	414	423	218	223
Percentage of AvailableForSaleSecuritiesDebtSecurities	76.3	81.2	72.5	55.4	43.7	37.9	48.9	61.8	66.6	78.5	79.2	80.9	81.5	66.0	0.0

us-gaap:CashUninsuredAmount

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31
Value	163	50	26	16
Percentage of CashUninsuredAmount	100.0	100.0	100.0	100.0

us-gaap:ContractWithCustomerAssetNet us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

us-gaap:ContractWithCustomerAssetNet

xncr:AlexionPharmaceuticalsInc, xncr:Milestone, xncr:OptionAndLicenseAgreement

Period End	2020-12-31
Value	10.0
Percentage of ContractWithCustomerAssetNet	100.0

xncr:Astellas, xncr:Milestone, xncr:ResearchAndLicenseAgreement

Period End	2020-12-31
Value	2.5
Percentage of ContractWithCustomerAssetNet	25.0

xncr:MorphoSys, us-gaap:Royalty, xncr:CollaborationAndLicenseAgreement

Period End	2020-12-31
Value	1.2
Percentage of ContractWithCustomerAssetNet	12.0

us-gaap:ContractWithCustomerAssetNet us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:AlexionPharmaceuticalsInc, xncr:OptionAndLicenseAgreement

Period End	2020-12-31	2019-12-31
Value	8.8	4.1
Percentage of ContractWithCustomerAssetNet	88.0	0.0

xncr:MorphoSys, xncr:CollaborationAndLicenseAgreement

Period End	2021-03-31
Value	12
Percentage of ContractWithCustomerAssetNet	0.0

xncr:Novartis, xncr:CollaborationAndLicenseAgreement

Period End	2020-12-31	2019-12-31	2019-06-30	2019-03-31
Value	0.9	12	3.0	2.0
Percentage of ContractWithCustomerAssetNet	9.0	0.0	0.0	0.0

xncr:VirBiotechnology, xncr:PatentLicenseAgreement

Period End	2021-06-30
Value	0.5
Percentage of ContractWithCustomerAssetNet	0.0

us-gaap:ContractWithCustomerAssetNet us-gaap:CounterpartyName, us-gaap:TypeOfArrangement, xncr:PotentialMilestonesType

xncr:MorphoSys, xncr:CollaborationAndLicenseAgreement, xncr:DevelopmentBasedMilestones

Period End	2021-03-31
Value	12
Percentage of ContractWithCustomerAssetNet	0.0

us-gaap:ContractWithCustomerAssetNetCurrent

Period End	2021-06-30	2021-03-31	2020-12-31
Value	0.5	12	12
Percentage of ContractWithCustomerAssetNetCurrent	100.0	100.0	100.0

us-gaap:ContractWithCustomerLiability

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	77	92	43	44	46	47	48	48	63	40	40	60	40
Percentage of ContractWithCustomerLiability	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ContractWithCustomerLiability us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

xncr:Genentech, xncr:ResearchActivity, xncr:CollaborationAndLicenseAgreement

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	2.3	2.5	3.7	4.6	5.4	6.1	6.8	7.5	8.0
Percentage of ContractWithCustomerLiability	3.0	2.7	8.4	10.3	11.7	13.0	14.1	15.4	12.7

us-gaap:ContractWithCustomerLiability us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31	2020-12-31
Value	19	35	50
Percentage of ContractWithCustomerLiability	100.0	45.5	54.0

xncr:Novartis, xncr:CollaborationAndLicenseAgreement

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	2018-09-30	2018-06-30	2018-03-31	2017-12-31
Value	40	40	40	40	40	40	40	40	40	40	40	60	60	60
Percentage of ContractWithCustomerLiability	51.5	43.3	91.6	89.7	86.8	85.1	83.2	82.2	63.5	100.0	100.0	100.0	149.9	0.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger

Period End	2021-06-30	2021-03-31	2019-12-31	2019-09-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	109	18	13	21	172	236	276	139
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

Period End	2021-06-30	2021-03-31	2020-03-31	2019-12-31	2019-09-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	24	3.066	38	13	21	12	20	28	43
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	22.7	17.0	0.0	100.0	100.0	7.3	8.6	10.3	31.6

us-gaap:USTreasuryAndGovernment

Period End	2021-06-30	2021-03-31	2020-09-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	84	14	31	159	215	247	95
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	77.3	83.0	0.0	92.7	91.4	89.7	68.4

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss

Period End	2021-06-30	2021-03-31	2019-09-30	2018-12-31	2018-09-30	2017-12-31
Value	50000.0	10000.0	9000.0	34000.0	1199000.0	1201000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

Period End	2021-06-30	2021-03-31	2020-03-31	2019-12-31	2019-09-30	2018-12-31	2018-09-30	2017-12-31
Value	27000.0	3000.0	189000.0	6000.0	9000.0	34000.0	60000.0	453000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	54.0	30.0	0.0	0.0	100.0	100.0	5.0	37.7

us-gaap:USTreasuryAndGovernment

Period End	2021-06-30	2021-03-31	2020-09-30	2018-12-31	2018-09-30	2017-12-31
Value	23000.0	7000.0	3000.0	132000.0	1139000.0	748000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	46.0	70.0	0.0	388.2	95.0	62.3

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months

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	2017-12-31
Value	11	4.102	56	46	18	52	318	268	236	207
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

Period End	2021-06-30	2021-03-31	2020-12-31	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	11	4.102	15	141	46	3.037	9.828	93	84	69	79
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	100.0	100.0	28.0	0.0	100.0	16.3	18.8	29.2	31.6	29.4	38.2

us-gaap:USTreasuryAndGovernment

Period End	2020-12-31	2020-09-30	2020-06-30	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	40	25	49	15	42	225	183	167	128
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	72.0	0.0	0.0	83.7	81.2	70.8	68.4	70.6	61.8

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss

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	2017-12-31
Value	4000.0	2000.0	9000.0	24000.0	2000.0	47000.0	186000.0	977000.0	1131000.0	598000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities

Period End	2021-06-30	2021-03-31	2020-12-31	2020-03-31	2019-12-31	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	4000.0	2000.0	6000.0	401000.0	24000.0	1000.0	2000.0	54000.0	310000.0	411000.0	137000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	100.0	100.0	66.7	0.0	100.0	50.0	4.3	29.0	31.7	36.3	22.9

us-gaap:USTreasuryAndGovernment

Period End	2020-12-31	2020-09-30	2020-06-30	2019-09-30	2019-06-30	2019-03-31	2018-12-31	2018-09-30	2017-12-31
Value	3000.0	1000.0	3000.0	1000.0	45000.0	132000.0	667000.0	720000.0	461000.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	33.3	0.0	0.0	50.0	95.7	71.0	68.3	63.7	77.1

us-gaap:DebtSecuritiesCurrent

Period End	2021-06-30	2021-03-31	2020-12-31	2019-12-31
Value	288	368	434	479
Percentage of DebtSecuritiesCurrent	100.0	100.0	100.0	100.0

us-gaap:DebtSecuritiesNoncurrent

Period End	2021-06-30	2021-03-31	2020-12-31	2019-12-31
Value	153	25	1.03	71
Percentage of DebtSecuritiesNoncurrent	100.0	100.0	100.0	100.0

us-gaap:DeferredIncomeTaxLiabilities

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	8955000.0	4318000.0	3298000.0	3051000.0	4044000.0	3892000.0	3587000.0	3454000.0
Percentage of DeferredIncomeTaxLiabilities	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsDeferredIncome

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	11	11	11	26	5.236	1.032	1.836	3.899
Percentage of DeferredTaxAssetsDeferredIncome	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsGross

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	114	81	85	70	73	79	63	87
Percentage of DeferredTaxAssetsGross	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

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	56	36	49	25	54	69	47	58
Percentage of DeferredTaxAssetsOperatingLossCarryforwards	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsPropertyPlantAndEquipment

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	137000.0	334000.0	207000.0	437000.0	668000.0	735000.0	790000.0	849000.0
Percentage of DeferredTaxAssetsPropertyPlantAndEquipment	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsTaxCreditCarryforwardsResearch

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	38	28	23	16	11	8.096	12	24
Percentage of DeferredTaxAssetsTaxCreditCarryforwardsResearch	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation

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	8464000.0	4788000.0	1097000.0	748000.0	719000.0	511000.0	373000.0	137000.0
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross

Period End	2020-12-31	2018-12-31	2017-12-31	2016-12-31
Value	195000.0	269000.0	504000.0	573000.0
Percentage of DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedPatentCosts

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	4219000.0	3736000.0	3142000.0	2873000.0	3725000.0	3489000.0	3199000.0	2929000.0
Percentage of DeferredTaxLiabilitiesDeferredExpenseCapitalizedPatentCosts	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:DeferredTaxLiabilitiesOtherComprehensiveIncome

Period End	2020-12-31	2019-12-31
Value	24000.0	327000.0
Percentage of DeferredTaxLiabilitiesOtherComprehensiveIncome	100.0	100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions us-gaap:AwardType

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions

us-gaap:RestrictedStockUnitsRSU

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2019-12-31	2018-12-31
Value	15	17	8.5	9.2	2.5	0.7
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions us-gaap:AwardType

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions

us-gaap:EmployeeStock

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	2016-06-30	2016-03-31	2015-12-31	2014-12-31
Value	0.5	0.7	0.9	1.1	1.3	1.3	1.4	0.1	0.4	0.2	0.8	1.0	1.2	0.162894	1.1	0.102176	0.242305	0.339	0.481	0.491	0.418	0.395	0.204
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:EmployeeStockOption

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	2016-06-30	2016-03-31	2015-12-31	2014-12-31	2013-12-31	2012-12-31
Value	65	71	48	53	59	62	51	56	63	64	42	44	47	49	30	33	35	35	18	16	16	10	7.6	0.895	0.026
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	13000.0	10200.0	5433.3	4881.8	4569.2	4784.6	3650.0	56600.0	15750.0	32350.0	5350.0	4450.0	3991.7	30572.0	2790.9	32590.8	14609.7	10442.5	3763.0	3319.8	3899.5	2734.2	3725.5	0.0	0.0

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount

Period End	2021-06-30	2021-03-31	2020-12-31
Value	17	28	16
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	100.0	100.0	100.0

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount us-gaap:CounterpartyName, us-gaap:StatementClassOfStock

xncr:CatabasisPharmaceuticalsInc, us-gaap:PreferredStock

Period End	2021-06-30
Value	1.075
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	6.3

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3

Period End	2021-06-30	2021-03-31	2020-12-31
Value	17	28	16
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	100.0	100.0	100.0

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31
Value	16
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	100.0

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring

Period End	2020-12-31
Value	16
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	100.0

us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueAmount us-gaap:StatementClassOfStock

us-gaap:PreferredStock

Period End	2021-06-30	2020-12-31
Value	17	16
Percentage of EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	100.0	100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3

Period End	2021-06-30	2020-12-31
Value	17	16
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	100.0	100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:Patents

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	5791000.0	4912000.0	4142000.0	3413000.0	2792000.0	2214000.0	1776000.0	1395000.0
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:LicensesAndOtherIntangibleAssets

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	1661000.0	1439000.0	1263000.0	1124000.0	960000.0	825000.0	679000.0	426000.0
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization	28.7	29.3	30.5	32.9	34.4	37.3	38.2	30.5

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

Period End	2020-12-31
Value	3208000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

Period End	2020-12-31
Value	947000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

Period End	2020-12-31
Value	589000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

Period End	2020-12-31
Value	667000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

Period End	2020-12-31
Value	829000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

Period End	2020-12-31
Value	906000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	100.0

us-gaap:FiniteLivedIntangibleAssetsGross us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsGross

xncr:LicensesAndOtherIntangibleAssets

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	2.56	2.51	2.011	2.011	2.011	2.072	1.797	1.917
Percentage of FiniteLivedIntangibleAssetsGross	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:PatentsDefiniteLife

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	12	10	9.32	8.915	7.57	6.488	5.72	4.834
Percentage of FiniteLivedIntangibleAssetsGross	470.2	422.2	463.5	443.3	376.4	313.1	318.3	252.2

xncr:PatentsPendingIssuance

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	8.432	7.266	5.644	4.36	4.134	4.051	3.654	3.515
Percentage of FiniteLivedIntangibleAssetsGross	329.4	289.5	280.7	216.8	205.6	195.5	203.3	183.4

us-gaap:IntangibleAssetsGrossExcludingGoodwill

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	23	20	17	15	14	13	11	10
Percentage of IntangibleAssetsGrossExcludingGoodwill	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:InterestReceivableCurrent

Period End	2020-12-31	2019-12-31
Value	1400000.0	2700000.0
Percentage of InterestReceivableCurrent	100.0	100.0

us-gaap:Investments

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	514	559	594	553	578	585	583	599	616	506	522	528	551	578	351
Percentage of Investments	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	2093000.0	2269000.0	2429000.0	2647000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	100.0	100.0	100.0	100.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear

Period End	2021-06-30	2021-03-31	2020-09-30
Value	1117000.0	1773000.0	655000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	100.0	100.0	100.0

us-gaap:MarketableSecuritiesNoncurrent

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
Value	31	1.145	38	71	73	120	172	236	276	299	120	139	163	190	237	273	197	77	86	96
Percentage of MarketableSecuritiesNoncurrent	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30	2019-12-31
Value	4.0	5.5	5.5	5.5	5.5
Percentage of OperatingLeaseWeightedAverageDiscountRatePercent	100.0	100.0	100.0	100.0	100.0

us-gaap:OperatingLossCarryforwards us-gaap:IncomeTaxAuthority

us-gaap:OperatingLossCarryforwards

us-gaap:DomesticCountry

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	213	144	191	104	145	181	169
Percentage of OperatingLossCarryforwards	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:StateAndLocalJurisdiction

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	161	92	138	50	91	127	134
Percentage of OperatingLossCarryforwards	75.6	64.1	72.7	48.6	63.1	70.4	79.3

us-gaap:OperatingLossCarryforwards us-gaap:IncomeTaxAuthority, us-gaap:TaxPeriod

us-gaap:DomesticCountry, us-gaap:TaxYear2018

Period End	2020-12-31	2019-12-31	2018-12-31
Value	145	76	88
Percentage of OperatingLossCarryforwards	68.2	53.0	46.4

us-gaap:DomesticCountry, xncr:YearsPriorTo2018

Period End	2020-12-31	2019-12-31	2018-12-31
Value	68	68	102
Percentage of OperatingLossCarryforwards	31.8	47.0	53.7

us-gaap:OtherCommitment us-gaap:CounterpartyName

us-gaap:OtherCommitment

xncr:UniversityOfTexasM.d.AndersonCancerCenter

Period End	2020-09-30
Value	10000000.0
Percentage of OtherCommitment	100.0

us-gaap:OtherCommitment us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:UniversityOfTexasM.d.AndersonCancerCenter, xncr:StrategicCollaborationAgreement

Period End	2020-08-31
Value	10000000.0
Percentage of OtherCommitment	0.0

us-gaap:RevenueRemainingPerformanceObligation us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

us-gaap:RevenueRemainingPerformanceObligation

xncr:Genentech, xncr:ResearchActivity, xncr:CollaborationAndLicenseAgreement

Period End	2020-12-31	2019-03-31	2019-02-28
Value	8.3	8.3	8.3
Percentage of RevenueRemainingPerformanceObligation	100.0	100.0	100.0

us-gaap:RevenueRemainingPerformanceObligation us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:AmgenInc, xncr:ResearchAndLicenseAgreement

Period End	2021-06-30	2019-12-31	2015-09-30
Value	0.9	60	45
Percentage of RevenueRemainingPerformanceObligation	0.0	0.0	0.0

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2020-11-30
Value	50
Percentage of RevenueRemainingPerformanceObligation	0.0

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement

Period End	2020-12-31
Value	6.0
Percentage of RevenueRemainingPerformanceObligation	72.3

xncr:OmerosCorporation, xncr:TechnologyLicenseAgreement

Period End	2020-08-31
Value	5.0
Percentage of RevenueRemainingPerformanceObligation	0.0

xncr:PrivateBiotechCompany, xncr:LicenseAgreement

Period End	2020-11-30
Value	16
Percentage of RevenueRemainingPerformanceObligation	0.0

xncr:ZenasBioPharmaLimited, xncr:LicenseAgreement

Period End	2020-11-30
Value	16
Percentage of RevenueRemainingPerformanceObligation	0.0

us-gaap:RevenueRemainingPerformanceObligation us-gaap:CounterpartyName, us-gaap:TypeOfArrangement, xncr:CollaborationAndLicensingPrograms

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement, xncr:XtendFcTechnologyLicenseAgreement

Period End	2020-12-31
Value	6.0
Percentage of RevenueRemainingPerformanceObligation	72.3

xncr:OmerosCorporation, xncr:TechnologyLicenseAgreement, xncr:InitialOptionExercises

Period End	2020-08-31
Value	3.0
Percentage of RevenueRemainingPerformanceObligation	0.0

xncr:OmerosCorporation, xncr:TechnologyLicenseAgreement, xncr:XtendFcTechnologyLicenseAgreement

Period End	2020-08-31
Value	2.0
Percentage of RevenueRemainingPerformanceObligation	0.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:RestrictedStockUnitsRSU

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	38.79	38.56	33.04	32.65	32.37	32.76	34.66	33.05	32.69	32.73	27.64
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-09-30
Value	5265800.0	4963600.0	4796500.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	100.0	100.0	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-09-30
Value	23.37	22.73	20.9
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	100.0	100.0	100.0

xncr:EmployeeAndNonEmployeeStockOption

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31	2013-12-31	2012-12-31
Value	21.75	17.79	15.12	11.06	8.87	3.99	1.01	0.59	0.59
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-12-31	2020-09-30
Value	65	125	134	107
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	100.0	100.0	100.0	100.0

xncr:EmployeeAndNonEmployeeStockOption

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	134	79	99	35	58	21	30	13
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	100.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue

xncr:EmployeeAndNonEmployeeStockOption

Period End	2020-12-31
Value	134
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue	100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice

xncr:EmployeeAndNonEmployeeStockOption

Period End	2020-12-31
Value	26.23
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice	100.0

us-gaap:SharePrice us-gaap:AwardType

us-gaap:SharePrice

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-09-30	2014-09-30	2014-06-30
Value	34.49	43.06	38.79	9.31	11.62
Percentage of SharePrice	100.0	100.0	100.0	100.0	100.0

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 us-gaap:AwardType

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:EmployeeStockOption

Period End	2021-06-30	2021-03-31	2020-09-30
Value	61	100	86
Percentage of SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	100.0	100.0	100.0

xncr:EmployeeAndNonEmployeeStockOption

Period End	2020-12-31
Value	102
Percentage of SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	0.0

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	21.75	17.79	15.12	11.06	8.87	3.99	1.01
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFive

Period End	2020-12-31	2019-12-31	2018-12-31
Value	37.51	39.85	38.93
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	172.5	224.0	257.5

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFour

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	30.12	27.64	23.08	24.13	16.2	16.52
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	138.5	155.4	152.6	218.2	182.6	414.0

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeOne

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	4.29	3.49	3.63	3.17	2.66	1.38	0.99
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	19.7	19.6	24.0	28.7	30.0	34.6	98.0

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeThree

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	22.67	20.62	16.35	15.68	11.31	11.11
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	104.2	115.9	108.1	141.8	127.5	278.4

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeTwo

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	13.1	12.19	11.97	11.64	5.55	7.09	5.5
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	60.2	68.5	79.2	105.2	62.6	177.7	544.6

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	26.23	24.03	19.71	15.32	11.95	8.5	5.12
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	100.0	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFive

Period End	2020-12-31	2019-12-31	2018-12-31	2016-12-31
Value	37.63	37.22	39.26	25.3
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	143.5	154.9	199.2	211.7

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFour

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	31.8	31.18	23.92	23.0	16.4	16.0
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	121.2	129.8	121.4	150.1	137.2	188.2

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeOne

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	4.29	3.49	3.63	3.17	2.83	1.87	1.63
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	16.4	14.5	18.4	20.7	23.7	22.0	31.8

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeThree

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	22.75	21.37	17.0	15.8	12.1	11.2	11.1
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	86.7	88.9	86.3	103.1	101.3	131.8	216.8

xncr:SharesAuthorizedUnderStockOptionPlansExercisePriceRangeTwo

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31	2014-12-31
Value	13.1	12.21	12.1	11.87	5.97	7.64	7.73
Percentage of SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	49.9	50.8	61.4	77.5	50.0	89.9	151.0

us-gaap:TaxCreditCarryforwardAmount us-gaap:IncomeTaxAuthority

us-gaap:TaxCreditCarryforwardAmount

us-gaap:DomesticCountry

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	26	19	14	10.0	6.4	3.9
Percentage of TaxCreditCarryforwardAmount	100.0	100.0	100.0	100.0	100.0	100.0

us-gaap:StateAndLocalJurisdiction

Period End	2020-12-31	2019-12-31	2018-12-31	2017-12-31	2016-12-31	2015-12-31
Value	14	11	8.2	6.6	5.2	4.2
Percentage of TaxCreditCarryforwardAmount	53.6	55.8	55.0	66.0	81.2	107.7

xncr:AnnualFundingAmount us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:AnnualFundingAmount

xncr:UniversityOfTexasM.d.AndersonCancerCenter, xncr:StrategicCollaborationAgreement

Period End	2020-08-31
Value	2000000.0
Percentage of AnnualFundingAmount	100.0

xncr:CashAndCashEquivalentsAndMarketableSecuritiesAmortizedCost

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	2019-03-31	2018-12-31	2018-03-31
Value	514	559	594	553	576	584	581	598	506	523	580
Percentage of CashAndCashEquivalentsAndMarketableSecuritiesAmortizedCost	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities us-gaap:CounterpartyName, us-gaap:ProductOrService, us-gaap:TypeOfArrangement

xncr:CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities

xncr:Genentech, xncr:Xmab24306Product, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30	2021-03-31	2020-09-30
Value	-2300000.0	-2900000.0	-1200000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	100.0	100.0	100.0

xncr:Novartis, xncr:Development, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30
Value	800000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	-34.8

xncr:Novartis, xncr:Milestone, xncr:CollaborationAndLicenseAgreement

Period End	2021-06-30
Value	1000000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	-43.5

xncr:CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:AlexionPharmaceuticalsInc, xncr:OptionAndLicenseAgreement

Period End	2020-09-30
Value	8100000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	-675.0

xncr:AtrecaInc., xncr:CollaborationAndLicenseAgreement

Period End	2020-09-30
Value	-100000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	8.3

xncr:Genentech, xncr:CollaborationAndLicenseAgreement

Period End	2020-12-31
Value	-3200000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	0.0

xncr:Novartis, xncr:CollaborationAndLicenseAgreement

Period End	2021-03-31	2020-09-30
Value	900000.0	1100000.0
Percentage of CollaborativeArrangementReceivablePayableRelatedToCostSharingDevelopmentActivities	-31.0	-91.7

xncr:DeferredTaxLiabilitiesCapitalizedLegalCosts

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	21000.0	26000.0	31000.0	36000.0	58000.0	64000.0	71000.0	119000.0
Percentage of DeferredTaxLiabilitiesCapitalizedLegalCosts	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:DeferredTaxLiabilitiesEquityInvestment

Period End	2020-12-31
Value	4497000.0
Percentage of DeferredTaxLiabilitiesEquityInvestment	100.0

xncr:DeferredTaxLiabilitiesLicenseCosts

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	194000.0	229000.0	125000.0	142000.0	261000.0	339000.0	317000.0	406000.0
Percentage of DeferredTaxLiabilitiesLicenseCosts	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0

xncr:EquitySecuritiesCurrent

Period End	2021-03-31	2020-12-31
Value	6136000.0	5303000.0
Percentage of EquitySecuritiesCurrent	100.0	100.0

xncr:EquitySecuritiesNoncurrent

Period End	2021-06-30	2021-03-31	2020-12-31
Value	17	28	16
Percentage of EquitySecuritiesNoncurrent	100.0	100.0	100.0

xncr:PercentageOfCoDetailingActivities us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:PercentageOfCoDetailingActivities

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2020-11-30
Value	30.0
Percentage of PercentageOfCoDetailingActivities	100.0

xncr:PercentageOfFundingForDevelopmentCosts us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:PercentageOfFundingForDevelopmentCosts

xncr:JanssenBiotechInc, xncr:CollaborationAndLicenseAgreement

Period End	2020-11-30
Value	20.0
Percentage of PercentageOfFundingForDevelopmentCosts	100.0

xncr:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount us-gaap:Range, us-gaap:AwardType

xncr:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount

srt:Maximum, us-gaap:EmployeeStock

Period End	2020-12-31	2019-12-31	2018-12-31
Value	15.0	0.15	0.15
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount	100.0	100.0	100.0

srt:Minimum, us-gaap:EmployeeStock

Period End	2020-12-31	2019-12-31	2018-12-31
Value	1.0	0.01	0.01
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount	6.7	6.7	6.7

Line plots across dimensions of each concept

TTM Greenblatt ROC
_
(None,)

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:IncomeStatementLocation
(None,)

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:AwardType
(None,)

us-gaap:ComprehensiveIncomeNetOfTax
us-gaap:StatementEquityComponents
(None,)

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ProductOrService
(None,)

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:CounterpartyName
(None,)

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:InvestmentType
(None,)

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType
(None,)

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)

us-gaap:ShareBasedCompensation
us-gaap:IncomeStatementLocation
(None,)

us-gaap:ShareBasedCompensation
us-gaap:AwardType
(None,)

XNCR

Table of contents

Plots across concepts

Tables

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted

Earnings Per Share Basic And Diluted

us-gaap:EarningsPerShareBasicAndDiluted

us-gaap:EarningsPerShareBasicAndDiluted

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType

us-gaap:EmployeeStock

us-gaap:EmployeeStockOption

us-gaap:RestrictedStockUnitsRSU

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:IncomeStatementLocation

us-gaap:GeneralAndAdministrativeExpense

us-gaap:ResearchAndDevelopmentExpense

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome

us-gaap:RetainedEarnings

General And Administrative Expense

us-gaap:GeneralAndAdministrativeExpense

us-gaap:GeneralAndAdministrativeExpense

Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

Interest Income Expense Net

us-gaap:InterestIncomeExpenseNet

us-gaap:InterestIncomeExpenseNet

Interest Paid Net

us-gaap:InterestPaidNet

us-gaap:InterestPaidNet

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense

Operating Expenses

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

xncr:CatabsisPharmaceuticalsInc, xncr:TechnologyLicenseAgreement

xncr:MiragenViridian, xncr:TechnologyLicenseAgreement

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss

Research And Development Expense

us-gaap:ResearchAndDevelopmentExpense

us-gaap:ResearchAndDevelopmentExpense

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax