Summary of Significant Accounting Policies - Contingent Consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 01, 2016	Feb. 29, 2016	Apr. 01, 2015	Jul. 01, 2014	Apr. 30, 2014
Fair value measurement of contingent consideration
Fair value of short-term contingent consideration			$ 9,354	$ 91,623
Fair value of long-term contingent consideration			1,799	803
Liability for contingent consideration
Balance as of beginning of period		$ 11,153	92,426	58,153
Changes in fair value: Increase (Decrease) in contingent consideration			(104)	44,257	$ 9,300
Net payments			(91,660)	(29,274)
Balance as of end of period			11,153	92,426	58,153
Forecast
Liability for contingent consideration
Changes in fair value: Increase (Decrease) in contingent consideration	$ (2,800)	$ (9,900)
Direct service costs and other operating expenses
Liability for contingent consideration
Changes in fair value: Increase (Decrease) in contingent consideration					6,200
Interest expense
Liability for contingent consideration
Changes in fair value: Increase (Decrease) in contingent consideration					$ 3,100
CDMI
Contingent consideration disclosures
Maximum potential contingent payments										$ 165,000
Remaining potential future payments			0
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments				90,100
4D Pharmacy Management Systems, Inc.
Contingent consideration disclosures
Maximum potential contingent payments								$ 30,000
Remaining potential future payments			0
Fair value measurement of contingent consideration
Estimated net undiscounted future contingent payments				1,000
Liability for contingent consideration
Acquisition				19,290
Cobalt
Contingent consideration disclosures
Maximum potential contingent payments									$ 6,000
Remaining potential future payments			5,000
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments			900	$ 1,700
Fair value of short-term contingent consideration			900
TMG
Contingent consideration disclosures
Maximum potential contingent payments							$ 15,000
Remaining potential future payments			15,000
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments			2,800				$ 3,800
Fair value of long-term contingent consideration			1,800
Liability for contingent consideration
Acquisition			2,244
AFSC
Contingent consideration disclosures
Maximum potential contingent payments						$ 10,000
Remaining potential future payments			10,000
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments			9,000			$ 9,000
Fair value of short-term contingent consideration			8,500
Liability for contingent consideration
Acquisition			8,247
Changes in fair value: Increase (Decrease) in contingent consideration			$ 300