Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended
	Sep. 30, 2010 customer	Mar. 31, 2013	Mar. 31, 2012
Operating results by business segment
Number of customers subcontracted by Public Sector with Medicaid Administration	1
Managed care and other revenue		$ 727,640	$ 686,059
Dispensing revenue		94,121	87,154
Cost of care		(529,931)	(505,293)
Cost of goods sold		(88,608)	(81,038)
Direct service costs and other		(139,627)	(136,589)
Stock compensation expense		5,638	5,102
Segment profit (loss)		69,233	55,395
Commercial
Operating results by business segment
Managed care and other revenue		187,837	180,524
Cost of care		(113,271)	(112,172)
Direct service costs and other		(41,392)	(42,362)
Stock compensation expense		133	267
Segment profit (loss)		33,307	26,257
Public Sector
Operating results by business segment
Managed care and other revenue		406,620	388,888
Cost of care		(355,379)	(344,312)
Direct service costs and other		(25,643)	(20,597)
Stock compensation expense		307	287
Segment profit (loss)		25,905	24,266
Radiology Benefits Management
Operating results by business segment
Managed care and other revenue		90,278	76,857
Cost of care		(58,067)	(50,410)
Direct service costs and other		(13,371)	(13,486)
Stock compensation expense		434	400
Segment profit (loss)		19,274	13,361
Pharmacy Solutions
Operating results by business segment
Managed care and other revenue		58,150	60,898
Dispensing revenue		94,121	87,154
Cost of care		(18,459)	(19,507)
Cost of goods sold		(88,608)	(81,038)
Direct service costs and other		(29,561)	(29,019)
Stock compensation expense		320	230
Segment profit (loss)		15,963	18,718
Corporate and Elimination
Operating results by business segment
Managed care and other revenue		(15,245)	(21,108)
Cost of care		15,245	21,108
Direct service costs and other		(29,660)	(31,125)
Stock compensation expense		4,444	3,918
Segment profit (loss)		$ (25,216)	$ (27,207)