Goodwill and Intangible Assets, Net - Intangible Assets, Net (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 31, 2018	Dec. 31, 2017	Oct. 01, 2018	Jan. 02, 2018	Mar. 01, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 403,438	$ 282,499
Accumulated Amortization		68,402	41,238
Net Carrying Amount		$ 335,036	$ 241,261
Corporate trade name
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life		15 years 2 months 15 days	17 years 5 months
Gross Carrying Amount		$ 23,300	$ 19,000
Accumulated Amortization		3,511	2,454
Net Carrying Amount		$ 19,789	$ 16,546
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life		18 years 1 month 10 days	20 years 6 months
Gross Carrying Amount		$ 281,219	$ 203,500
Accumulated Amortization		29,184	18,312
Net Carrying Amount		$ 252,035	$ 185,188
Technology
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life		3 years	3 years 1 month 15 days
Gross Carrying Amount		$ 82,922	$ 55,802
Accumulated Amortization		31,764	17,810
Net Carrying Amount		$ 51,158	$ 37,992
Below market lease, net
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life		4 years	4 years 10 months
Gross Carrying Amount		$ 4,097	$ 4,197
Accumulated Amortization		3,003	2,662
Net Carrying Amount		$ 1,094	$ 1,535
Provider network contracts
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life		4 years 7 months 12 days
Gross Carrying Amount		$ 11,900
Accumulated Amortization		940
Net Carrying Amount		$ 10,960
New Century Health | Corporate trade name
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets				$ 4,300
New Century Health | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets				72,500
New Century Health | Technology
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets				27,000
New Century Health | Provider network contracts
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets				$ 9,600
New Mexico Health Connections
Finite-Lived Intangible Assets [Line Items]
Contingent consideration, liability					$ 252
New Mexico Health Connections | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets					2,700
New Mexico Health Connections | Provider network contracts
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets					2,300
Vestica
Finite-Lived Intangible Assets [Line Items]
Contingent consideration, liability						$ 4,000
Contingent consideration settled	$ 3,500
Vestica | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets					$ 2,500