Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Operating results by business segment
Managed care and other revenue	$ 703,020	$ 770,113	$ 2,214,885	$ 2,239,422
PBM and dispensing revenue	220,150	103,485	562,774	298,685
Cost of care	(495,180)	(564,537)	(1,582,505)	(1,627,194)
Cost of goods sold	(202,180)	(97,503)	(520,044)	(281,190)
Direct service costs and other	(176,928)	(156,834)	(520,684)	(440,958)
Stock compensation expense	11,961	4,524	25,983	14,764
Less: non-controlling interest segment profit (loss)	(1,323)		(3,301)
Segment profit (loss)	62,166	59,248	183,710	203,529
Operating segments | Commercial
Operating results by business segment
Managed care and other revenue	144,257	190,655	531,173	578,030
Cost of care	(71,264)	(118,022)	(299,318)	(354,520)
Direct service costs and other	(37,513)	(47,032)	(120,319)	(129,823)
Stock compensation expense	164	124	476	390
Segment profit (loss)	35,644	25,725	112,012	94,077
Operating segments | Public Sector
Operating results by business segment
Managed care and other revenue	388,682	445,260	1,206,579	1,266,739
Cost of care	(337,128)	(382,913)	(1,034,754)	(1,095,694)
Direct service costs and other	(45,789)	(27,826)	(134,138)	(82,403)
Stock compensation expense	225	259	729	833
Less: non-controlling interest segment profit (loss)	(1,323)		(3,301)
Segment profit (loss)	7,313	34,780	41,717	89,475
Operating segments | Specialty Solutions
Operating results by business segment
Managed care and other revenue	120,808	94,125	345,568	277,118
Cost of care	(86,787)	(65,403)	(250,192)	(182,212)
Direct service costs and other	(17,843)	(13,990)	(50,881)	(41,224)
Stock compensation expense	269	384	1,037	1,275
Segment profit (loss)	16,447	15,116	45,532	54,957
Operating segments | Pharmacy Management
Operating results by business segment
Managed care and other revenue	49,273	57,164	149,620	166,092
PBM and dispensing revenue	241,226	103,485	590,115	298,685
Cost of care	(1)	(15,290)	(16,296)	(43,325)
Cost of goods sold	(223,251)	(97,503)	(547,362)	(281,190)
Direct service costs and other	(45,535)	(32,281)	(122,691)	(93,216)
Stock compensation expense	8,122	198	13,981	898
Segment profit (loss)	29,834	15,773	67,367	47,944
Corporate and Elimination
Operating results by business segment
Managed care and other revenue		(17,091)	(18,055)	(48,557)
PBM and dispensing revenue	(21,076)		(27,341)
Cost of care		17,091	18,055	48,557
Cost of goods sold	21,071		27,318
Direct service costs and other	(30,248)	(35,705)	(92,655)	(94,292)
Stock compensation expense	3,181	3,559	9,760	11,368
Segment profit (loss)	$ (27,072)	$ (32,146)	$ (82,918)	$ (82,924)