Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended
	Sep. 30, 2010 customer	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating results by business segment
Number of customers subcontracted by Public Sector with Medicaid Administration	1
Net revenue		$ 721,464	$ 686,843	$ 698,338	$ 692,755	$ 749,210	$ 750,319	$ 741,658	$ 728,053	$ 2,799,400	$ 2,969,240	$ 2,641,814
Cost of care		(461,527)	(448,051)	(441,446)	(433,700)	(491,668)	(467,160)	(472,478)	(476,679)	(1,784,724)	(1,907,985)	(1,765,313)
Cost of goods sold		(64,479)	(57,636)	(53,404)	(56,519)	(52,492)	(55,071)	(54,771)	(56,296)	(232,038)	(218,630)	(203,336)
Direct service costs										(409,266)	(442,207)	(351,622)
Other operating expenses										(120,368)	(124,375)	(114,088)
Stock compensation expense		(4,010)	(4,425)	(4,205)	(4,778)	(3,272)	(3,596)	(3,706)	(4,528)	(17,418)	(15,102)	(19,782)
Segment profit (loss)										270,422	291,145	227,237
Identifiable assets by business segment
Restricted cash		185,794				116,734				185,794	116,734	159,659
Net accounts receivable		121,606				106,934				121,606	106,934	114,434
Investments		200,903				284,504				200,903	284,504	230,445
Goodwill		426,939				426,939				426,939	426,939	426,471
Commercial
Operating results by business segment
Net revenue										561,780	652,221	650,139
Cost of care										(314,178)	(365,115)	(351,270)
Direct service costs										(152,760)	(156,278)	(152,280)
Stock compensation expense										839	714	953
Segment profit (loss)										95,681	131,542	147,542
Identifiable assets by business segment
Restricted cash		18,319				22,501				18,319	22,501	20,398
Net accounts receivable		26,822				26,564				26,822	26,564	23,025
Investments		5,320				8,507				5,320	8,507	14,337
Goodwill		120,485				120,485				120,485	120,485	120,485
Public Sector
Operating results by business segment
Net revenue										1,459,659	1,442,093	1,362,420
Cost of care										(1,271,532)	(1,246,779)	(1,208,451)
Direct service costs										(67,227)	(67,577)	(67,835)
Stock compensation expense										872	714	690
Segment profit (loss)										121,772	128,451	86,824
Identifiable assets by business segment
Restricted cash		164,479				82,813				164,479	82,813	133,123
Net accounts receivable		28,331				15,086				28,331	15,086	16,450
Investments		131,261				183,632				131,261	183,632	133,392
Radiology Benefits Management
Operating results by business segment
Net revenue										344,335	454,105	305,251
Cost of care										(205,240)	(298,516)	(205,592)
Direct service costs										(61,681)	(67,672)	(51,732)
Stock compensation expense										1,563	1,485	1,260
Segment profit (loss)										78,977	89,402	49,187
Identifiable assets by business segment
Restricted cash						7,890					7,890	2,272
Net accounts receivable		1,398				2,496				1,398	2,496	6,085
Investments						5,005					5,005	12,676
Goodwill		104,549				104,549				104,549	104,549	104,549
Specialty Pharmaceutical Management
Operating results by business segment
Net revenue										295,943	270,646	259,745
Cost of goods sold										(232,038)	(218,630)	(203,336)
Direct service costs										(24,344)	(26,368)	(24,901)
Stock compensation expense										693	424	5,383
Segment profit (loss)										40,254	26,072	36,891
Identifiable assets by business segment
Net accounts receivable		21,370				28,309				21,370	28,309	30,371
Goodwill		142,291				142,291				142,291	142,291	142,291
Medicaid Administration
Operating results by business segment
Net revenue										220,453	176,283	64,259
Cost of care										(76,544)	(23,683)
Direct service costs										(103,254)	(124,312)	(54,874)
Stock compensation expense										124	74	27
Segment profit (loss)										40,779	28,362	9,412
Identifiable assets by business segment
Net accounts receivable		30,654				29,632				30,654	29,632	31,021
Goodwill		59,614				59,614				59,614	59,614	59,146
Corporate and Elimination
Operating results by business segment
Net revenue										(82,770)	(26,108)
Cost of care										82,770	26,108
Other operating expenses										(120,368)	(124,375)	(114,088)
Stock compensation expense										13,327	11,691	11,469
Segment profit (loss)										(107,041)	(112,684)	(102,619)
Identifiable assets by business segment
Restricted cash		2,996				3,530				2,996	3,530	3,866
Net accounts receivable		13,031				4,847				13,031	4,847	7,482
Investments		$ 64,322				$ 87,360				$ 64,322	$ 87,360	$ 70,040