Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Operating results by business segment
Managed care and other revenue	$ 682,274		$ 746,720		$ 1,511,865		$ 1,469,309
PBM and dispensing revenue	205,740		96,028		342,624		195,200
Cost of care	(481,617)		(537,630)		(1,087,325)		(1,062,657)
Cost of goods sold	(192,566)		(90,175)		(317,864)		(183,687)
Direct service costs and other	(179,034)	[1]	(144,497)	[1]	(343,756)	[1]	(284,124)	[1]
Stock compensation expense	9,550		4,602		14,022		10,240
Less: non-controlling interest segment profit (loss)	(648)				(1,978)
Segment profit (loss)	44,995		75,048		121,544		144,281
Operating segments | Commercial
Operating results by business segment
Managed care and other revenue	198,025		199,538		386,916		387,375
Cost of care	(116,852)		(123,227)		(228,054)		(236,498)
Direct service costs and other	(42,530)		(41,399)		(82,806)		(82,791)
Stock compensation expense	157		133		312		266
Segment profit (loss)	38,800		35,045		76,368		68,352
Operating segments | Public Sector
Operating results by business segment
Managed care and other revenue	319,954		414,859		817,897		821,479
Cost of care	(275,108)		(357,402)		(697,626)		(712,781)
Direct service costs and other	(45,391)		(28,934)		(88,349)		(54,577)
Stock compensation expense	230		267		504		574
Less: non-controlling interest segment profit (loss)	(648)				(1,978)
Segment profit (loss)	333		28,790		34,404		54,695
Operating segments | Specialty Solutions
Operating results by business segment
Managed care and other revenue	119,326		92,715		224,760		182,993
Cost of care	(89,753)		(58,742)		(163,405)		(116,809)
Direct service costs and other	(17,897)		(13,863)		(33,038)		(27,234)
Stock compensation expense	354		457		768		891
Segment profit (loss)	12,030		20,567		29,085		39,841
Operating segments | Pharmacy Management
Operating results by business segment
Managed care and other revenue	44,969		55,829		100,347		108,928
PBM and dispensing revenue	209,265		96,028		348,889		195,200
Cost of care	96		(14,480)		(16,295)		(28,035)
Cost of goods sold	(196,080)		(90,175)		(324,111)		(183,687)
Direct service costs and other	(41,605)		(31,374)		(77,156)		(60,935)
Stock compensation expense	5,556		380		5,859		700
Segment profit (loss)	22,201		16,208		37,533		32,171
Corporate and Elimination
Operating results by business segment
Managed care and other revenue			(16,221)		(18,055)		(31,466)
PBM and dispensing revenue	(3,525)				(6,265)
Cost of care			16,221		18,055		31,466
Cost of goods sold	3,514				6,247
Direct service costs and other	(31,611)		(28,927)		(62,407)		(58,587)
Stock compensation expense	3,253		3,365		6,579		7,809
Segment profit (loss)	$ (28,369)		$ (25,562)		$ (55,846)		$ (50,778)

[1] Includes stock compensation expense of $4,602 and $9,550 for the three months ended June 30, 2013 and 2014, respectively, and $10,240 and $14,022 for the six months ended June 30, 2013 and 2014, respectively.