General - Revenues and Significant Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Net revenues
Managed Care Revenue	$ 647,200	$ 570,800	$ 1,206,300	$ 1,115,800
Fee-For-Service, Fixed Fee and Cost-Plus Contracts Revenue	144,200	102,600	287,900	205,600
Rebate Revenues	21,200	21,300	43,500	41,100
PBM Revenue	436,000	362,000	868,900	697,000
Dispensing Revenue	53,200	54,400	108,400	109,700
Medicare Part D Revenues	124,500	65,200	236,100	115,500
Co-payments	16,300	7,600	39,700	17,100
Medicare Part D Receivables	146,300		146,300		$ 117,500
Revenues	$ 1,419,139	$ 1,164,345	$ 2,724,762	2,281,367
Florida Medicaid Contract
Net revenues
Termination notice			1 day
Termination notice period without cause			30 days
Florida Contracts
Net revenues
Revenues			$ 300,100	267,800
Pharmacy Management | Customer A
Net revenues
Revenues			2,690	$ 193,956
Pharmacy Management | Customer B
Net revenues
Revenues			$ 184,364