Business Segment Information - Identifiable Assets by Business Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment reporting information
Restricted cash	$ 49,227	$ 51,253	$ 56,211
Accounts receivable, net	743,502	680,569	657,734
Investments	143,459	101,661	98,878
Pharmaceutical inventory	43,334	44,962	40,818
Goodwill	873,779	806,421	806,421
Other intangible assets, net	79,689	81,675	128,132
Operating Segments | Healthcare
Segment reporting information
Restricted cash	33,381	49,027	52,681
Accounts receivable, net	229,250	201,462	192,239
Investments	136,243	94,943	91,841
Goodwill	478,227	410,869	410,869
Other intangible assets, net	39,446	20,059	32,893
Operating Segments | Pharmacy Management
Segment reporting information
Restricted cash	12,658	2,226	576
Accounts receivable, net	509,086	478,627	465,345
Investments	7,216	6,718	7,037
Pharmaceutical inventory	43,334	44,962	40,818
Goodwill	395,552	395,552	395,552
Other intangible assets, net	40,243	61,536	82,072
Corporate and Eliminations
Segment reporting information
Restricted cash	3,188		2,954
Accounts receivable, net	$ 5,166	480	150
Other intangible assets, net		$ 80	$ 13,167