Quarterly Information (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 2,837,800,000	[1]	$ 2,779,600,000		$ 2,841,300,000		$ 2,830,400,000		$ 2,708,000,000		$ 2,692,000,000		$ 2,652,300,000		$ 3,363,200,000		$ 11,289,092,000	$ 11,415,436,000	$ 13,115,417,000
Health plan services costs	2,332,800,000		2,281,400,000		2,358,500,000		2,343,700,000		2,149,900,000		2,149,300,000		2,123,300,000		2,117,300,000		9,316,313,000	8,539,754,000	8,219,832,000
Government contracts costs	137,500,000		151,800,000		153,400,000		162,300,000		157,000,000		127,900,000		130,800,000		822,200,000		605,074,000	1,237,884,000	3,168,160,000
Income (loss) from operations before income taxes	8,400,000		29,400,000		7,400,000		(13,600,000)		63,500,000		92,900,000		86,200,000		(80,800,000)		31,650,000	161,764,000	280,612,000
Loss (income) on discontinued operation, net of tax	(2,200,000)		(2,500,000)		119,400,000		(18,500,000)		17,100,000		4,000,000		1,500,000		(11,600,000)		96,382,000	11,064,000	32,358,000
Net income (loss)	6,000,000	[1],[2]	18,000,000	[3]	124,600,000	[4]	(26,600,000)	[5]	60,200,000	[6]	61,800,000	[7]	58,300,000	[8]	(108,200,000)	[9]	122,063,000	72,120,000	204,243,000
Basic (loss) earnings per share from continuing operations	$ 0.10		$ 0.25		$ 0.06		$ (0.10)		$ 0.52		$ 0.66		$ 0.63		$ (1.04)		$ 0.31	$ 0.69	$ 1.75
Diluted (loss) earnings per share from continuing operations	$ 0.10	[10]	$ 0.25	[10]	$ 0.06	[10]	$ (0.10)	[10]	$ 0.51	[11]	$ 0.65	[11]	$ 0.62	[11]	$ (1.04)	[11]	$ 0.31	$ 0.68	$ 1.73
Basic (loss) earnings per share on discontinued operation	$ (0.03)		$ (0.03)		$ 1.44		$ (0.22)		$ 0.21		$ 0.05		$ 0.01		$ (0.12)		$ 1.18	$ 0.12	$ 0.33
Diluted (loss) earnings per share on discontinued operation	$ (0.03)	[10]	$ (0.03)	[10]	$ 1.42	[10]	$ (0.22)	[10]	$ 0.20	[11]	$ 0.05	[11]	$ 0.01	[11]	$ (0.12)	[11]	$ 1.16	$ 0.12	$ 0.33
Basic (loss) earnings per share	$ 0.07		$ 0.22		$ 1.50		$ (0.32)		$ 0.73		$ 0.71		$ 0.64		$ (1.16)		$ 1.49	$ 0.81	$ 2.08
Diluted (loss) earnings per share	$ 0.07	[10]	$ 0.22	[10]	$ 1.48	[10]	$ (0.32)	[10]	$ 0.71	[11]	$ 0.70	[11]	$ 0.63	[11]	$ (1.16)	[11]	$ 1.47	$ 0.80	$ 2.06
Payments for legal settlements															177,200,000
G&A cost reduction efforts expense	8,200,000		7,200,000		10,800,000		9,500,000
Adjustment to loss on sale of Northeast health plan subsidiaries													(6,300,000)		(34,900,000)		0	(40,815,000)	(41,959,000)
Litigation reserve true-up							700,000		6,300,000		200,000		300,000
Insurance reimbursement related to prior litigation							6,500,000
Gain on sale of discontinued operation, net of tax	(2,200,000)		(2,400,000)		119,400,000												114,834,000	0	0
Operations strategy and other cost management initiatives charge									9,700,000		4,700,000		2,700,000		11,000,000
Contract breakage cost	5,000,000
Litigation related expenses	7,100,000
Medicaid Retro Rate Adjustment	31,500,000																21,700,000
Incurred claims from prior years [Member]
Health plan services costs					$ 7,900,000		$ 25,000,000										$ 35,000,000	$ (97,000,000)

[1] Includes $31.5 million of premium revenue as a result of Medicaid/Medi-Cal retroactive rate adjustment related to the third quarter of 2012 and prior periods.

[2] Includes a $2.2 million unfavorable adjustment to the gain on sale of discontinued operation, an $8.2 million expense related to our G&A cost reduction efforts, a $5.0 million expense related to the early termination of a medical management contract and $7.1 million of litigation-related expenses.

[3] Includes a $2.4 million unfavorable adjustment to the gain on sale of discontinued operation and a $7.2 million expense related to our G&A cost reduction efforts.

[4] Includes $119.4 million gain on sale of discontinued operation related to the sale of our Medicare PDP business to CVS Caremark. Also, includes $7.9 million of adverse development related to prior years recorded as part of health care costs, and a $10.8 million expense related to our G&A cost reduction efforts.

[5] Includes $25.0 million of adverse development related to prior periods recorded as part of health care costs, a $9.5 million expense related to our G&A cost reduction efforts and an unfavorable $0.7 million in pretax litigation reserve adjustment. Also includes a $6.5 million insurance reimbursement related to a prior legal settlement.

[6] Includes a $9.7 million expense related to our cost management initiatives and a $6.3 million benefit from litigation reserve adjustments

[7] Includes a $4.7 million expense related to our cost management initiatives and a $0.2 million benefit from litigation reserve adjustments

[8] Includes a $2.7 million expense related to our cost management initiatives, a $0.3 million benefit from litigation reserve adjustments and a $6.3 million favorable adjustment to loss on sale of Northeast health plan subsidiaries.

[9] Includes a $177.2 million expense incurred as a result of the Louisiana Supreme Court’s judgment in the AmCareco litigation, an $11.0 million expense related to our cost management initiatives and a $34.9 million favorable adjustment to loss of sale of Northeast health plan subsidiaries.

[10] The sum of the quarterly amounts may not equal the year-to-date amounts due to rounding.

[11] The sum of the quarterly amounts may not equal the year-to-date amounts due to rounding