Held for Sale and Discontinued Operations - Additional Information (Details) $ in Thousands			3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 19, 2019 USD ($)	Dec. 05, 2017	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 18, 2019 USD ($) clinic	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of discontinued operations before taxes						$ 0	$ (24,248)	$ (23,022)
Proceeds from sale of DMG division	$ 4,465,476
Proceeds from Divestiture of Businesses, Net of Cash Divested	$ 3,824,509
Gain (Loss) on Disposition of Business						0	(16,252)	0
Payments to Acquire Businesses, Gross						187,050	182,013	100,861
Series of individually immaterial business acquisitions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to Acquire Businesses, Gross						$ 187,050	182,013	98,836
DMG Acquisitions | Series of individually immaterial business acquisitions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses acquired | clinic					2
Payments to Acquire Businesses, Gross					$ 2,025
Business combination, deferred purchase price					$ 212
Discontinued Operations, Held-for-sale | DMG - discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Sale, Effective Date Of Sale	Jun. 19, 2019
Purchase And Sale Agreement Aggregate Purchase Price	$ 4,340,000
Business Sale, Date Of Purchase And Sale Agreement		Dec. 05, 2017
Loss on sale of discontinued operations before taxes							$ (7,996)	$ (23,022)
Additional Payment To The Buyer Related To The Final Agreement On The Purchase Price			$ 47,000
Gain (Loss) on Disposition of Business			$ (17,976)
Discontinued Operations, Held-for-sale | DMG - discontinued operations | Coronavirus Aid Relief And Economic Security Act Additional Tax Benefit Member [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business				$ 9,980