Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 3,758,400		$ 3,789,900		$ 3,421,400		$ 3,038,900		$ 2,743,200	$ 2,775,000	$ 2,738,400	$ 2,797,000	$ 14,008,586	$ 11,053,743	$ 11,289,092
Net investment income													45,166	69,613	82,434
Administrative services fees and other income													(1,725)	34,791	17,968
Divested operations and services revenue													0	0	40,471
Interest Expense													31,376	32,614	33,220
Depreciation and amortization													29,786	38,589	31,146
Share-based compensation expense													28,334	29,930	28,893
Segment pretax income (loss)	16,300	[1],[2]	22,700	[3],[4]	98,800	[5]	62,000	[6]	28,000	108,600	52,000	81,300	199,792	269,953	31,650
Corporate/Other/Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues													0	0	0
Segment pretax income (loss)													(185,300)	(12,000)	(42,000)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues													13,965,200	10,949,400	11,148,200
Operating Segments [Member] | Western Region Operations [Member]
Segment Reporting Information [Line Items]
Revenues													13,361,200	10,377,100	10,459,100
Net investment income													45,200	69,600	82,400
Administrative services fees and other income													(1,700)	34,800	18,000
Divested operations and services revenue															0
Interest Expense													31,400	32,600	33,200
Depreciation and amortization													29,700	38,600	31,100
Share-based compensation expense													25,000	26,100	24,100
Segment pretax income (loss)													315,600	207,500	29,200
Operating Segments [Member] | Government Contracts [Member]
Segment Reporting Information [Line Items]
Revenues													604,000	572,300	689,100
Net investment income													0	0	0
Administrative services fees and other income													0	0	0
Divested operations and services revenue															0
Interest Expense													0	0	0
Depreciation and amortization													0	0	0
Share-based compensation expense													3,300	3,800	4,200
Segment pretax income (loss)													69,500	74,500	89,900
Operating Segments [Member] | Divested Operations and Services [Member]
Segment Reporting Information [Line Items]
Revenues															0
Net investment income															0
Administrative services fees and other income															0
Divested operations and services revenue															40,500
Interest Expense															0
Depreciation and amortization															0
Share-based compensation expense															600
Segment pretax income (loss)															(45,400)
Intersegment eliminations [Member]
Segment Reporting Information [Line Items]
Revenues													0	0	0
Intersegment eliminations [Member] | Western Region Operations [Member]
Segment Reporting Information [Line Items]
Revenues													12,400	11,100	11,000
Intersegment eliminations [Member] | Government Contracts [Member]
Segment Reporting Information [Line Items]
Revenues													0	0	0
Intersegment eliminations [Member] | Divested Operations and Services [Member]
Segment Reporting Information [Line Items]
Revenues															0
Intersegment eliminations [Member] | Corporate/Other/Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues													$ (12,400)	$ (11,100)	$ (11,000)

[1] Includes $3.8 million pretax asset impairment primarily related to our assets held for sale in connection with the Cognizant Transaction and $68.3 million in pretax expenses primarily related to the Cognizant Transaction.

[2] ncludes $35.4 million amortization of deferred costs of health insurer's fee and $25.8 million in other ACA fees.

[3] Includes $31.9 million amortization of deferred costs of health insurer's fee and $26.6 million in other ACA fees.

[4] Includes $84.7 million pretax asset impairment related to our assets held for sale in connection with the Cognizant Transaction and $21.1 million in pretax expenses primarily related to the Cognizant transaction.

[5] Includes $37.8 million amortization of deferred costs of health insurer's fee and $22.5 million in other ACA fees.

[6] Includes $36.3 million amortization of deferred costs of health insurer's fee and $22.5 million in other ACA fees.