Basis of Presentation and Principles of Consolidation - VIE (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) item	Jun. 30, 2021 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Variable interest entity
Number of professional associations consolidated as VIEs | item			3
Number of professional corporations consolidated as VIEs | item			12
Revenue	$ 592,379	$ 503,139	$ 1,157,729	$ 956,814
Net (loss) income	(3,101,461)	(133,819)	(9,775,984)	(333,468)
Assets	8,102,775		8,102,775			$ 17,734,608
(Equity) deficit	(6,084,650)	(16,001,070)	(6,084,650)	(16,001,070)	$ (9,142,610)	(16,045,757)	$ (15,829,498)	$ (15,883,804)
Primary beneficiary
Variable interest entity
Revenue	59,300	56,500	119,400	110,700
Net (loss) income	(500)	$ (100)	(2,800)	$ 1,300
Assets	18,800		18,800			58,500
Liabilities	57,700		57,700			94,600
(Equity) deficit	$ 38,900		$ 38,900			$ 36,100