Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 customer	Jun. 30, 2011
Operating results by business segment
Net revenue	$ 805,473	$ 698,338	$ 1,578,686	$ 1,391,093
Cost of care	(521,830)	(441,446)	(1,027,123)	(875,146)
Cost of goods sold	(82,855)	(53,404)	(163,893)	(109,923)
Direct service costs	(106,290)	(103,388)	(211,754)	(206,875)
Other operating expenses	(34,043)	(28,391)	(65,168)	(56,471)
Stock compensation expense	(4,365)	(4,205)	(9,467)	(8,983)
Segment profit (loss)	64,820	75,914	120,215	151,661
Number of customers subcontracted by Public Sector with Medicaid Administration			1
Commercial
Operating results by business segment
Net revenue	178,227	139,686	358,751	289,721
Cost of care	(110,847)	(79,122)	(223,019)	(154,435)
Direct service costs	(42,456)	(39,112)	(84,818)	(76,920)
Stock compensation expense	270	218	537	469
Segment profit (loss)	25,194	21,670	51,451	58,835
Public Sector
Operating results by business segment
Net revenue	410,136	362,284	799,024	712,800
Cost of care	(355,113)	(309,934)	(699,425)	(614,855)
Direct service costs	(23,304)	(16,486)	(43,901)	(33,462)
Stock compensation expense	269	214	556	436
Segment profit (loss)	31,988	36,078	56,254	64,919
Radiology Benefits Management
Operating results by business segment
Net revenue	88,826	90,608	165,683	179,820
Cost of care	(57,874)	(53,828)	(108,284)	(108,545)
Direct service costs	(13,582)	(15,858)	(27,068)	(32,563)
Stock compensation expense	360	401	760	883
Segment profit (loss)	17,730	21,323	31,091	39,595
Specialty Pharmaceutical Management
Operating results by business segment
Net revenue	101,976	69,366	202,174	139,596
Cost of goods sold	(82,855)	(53,404)	(163,893)	(109,923)
Direct service costs	(6,206)	(6,083)	(12,673)	(12,095)
Stock compensation expense	152	133	324	259
Segment profit (loss)	13,067	10,012	25,932	17,837
Medicaid Administration
Operating results by business segment
Net revenue	43,026	56,637	90,880	109,930
Cost of care	(14,714)	(18,805)	(34,221)	(38,085)
Direct service costs	(20,742)	(25,849)	(43,294)	(51,835)
Stock compensation expense	84	41	142	64
Segment profit (loss)	7,654	12,024	13,507	20,074
Corporate and Elimination
Operating results by business segment
Net revenue	(16,718)	(20,243)	(37,826)	(40,774)
Cost of care	16,718	20,243	37,826	40,774
Other operating expenses	(34,043)	(28,391)	(65,168)	(56,471)
Stock compensation expense	3,230	3,198	7,148	6,872
Segment profit (loss)	(30,813)	(25,193)	(58,020)	(49,599)
Unallocated Amount To Segment
Operating results by business segment
Stock compensation expense	$ 4,365	$ 4,205	$ 9,467	$ 8,983