Held for Sale and Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended				11 Months Ended	12 Months Ended
	Jun. 01, 2018	Dec. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Dec. 10, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Valuation adjustment on disposal group								$ 316,840	$ 0	$ 0
Goodwill impairment charges								3,106	36,196	28,415
Payments to Acquire Businesses, Gross								183,156	803,879	563,856
DMG
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of DMG division		$ 4,340,000					$ 4,900,000
Goodwill impairment charges					$ 601,040	$ 50,619
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								176,161	308,550	165,108
Business combination, liabilities assumed								34,394	23,748	17,963
DMG Acquisitions | 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								6,995	135,416	398,748
Business combination, deferred purchase price								1,142	1,038
Business combination, liabilities assumed									10,145
Business combination, deferred purchase price and liabilities assumed										7,694
Discontinued Operations, Held-for-sale | DMG
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Valuation charge to record valuation allowance and related tax expense, disposal group, including discontinued operations				$ (216,147)				(468,005)
Valuation adjustment on disposal group			$ 218,639	98,201				316,840
Goodwill impairment charges			41,537					41,537	$ 651,659	$ 253,000
Tax expense related to valuation adjustment, disposal group, including discontinued operation			$ 8,318	$ 117,946				109,628
Tandigm Health
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership sold	19.00%
Equity Method Investment, Realized Gain (Loss) on Disposal								25,096
Tax related to gain on sale of equity investment								$ 6,460
Gain (loss) on disposition of business, net of tax	$ 18,636