Schedule I, Condensed Financial Information of Parent Company (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	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	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 1,399,162,000					$ 1,579,003,000					$ 1,399,162,000	$ 1,579,003,000	$ 1,853,988,000
Short-term investments	121,742,000					116,205,000					121,742,000	116,205,000
Other receivables, net	892,815,000					717,736,000					892,815,000	717,736,000
Other current assets	196,323,000					286,301,000					196,323,000	286,301,000
Total current assets	2,882,119,000					2,969,508,000					2,882,119,000	2,969,508,000
Long-term investments	2,658,582,000					2,635,309,000					2,658,582,000	2,635,309,000
Property and equipment, net	266,818,000					255,485,000					266,818,000	255,485,000
Other long-term assets	33,389,000					36,863,000					33,389,000	36,863,000
Total assets	8,750,988,000					8,813,532,000					8,750,988,000	8,813,532,000
Current liabilities:
Accounts payable and other accrued liabilities	488,175,000					695,235,000					488,175,000	695,235,000
Total current liabilities	2,045,070,000					2,352,155,000					2,045,070,000	2,352,155,000
Long-term debt	1,585,190,000					1,584,700,000					1,585,190,000	1,584,700,000
Other long-term liabilities	397,813,000					365,686,000					397,813,000	365,686,000
Total liabilities	4,028,073,000					4,302,541,000					4,028,073,000	4,302,541,000
Stockholders’ equity:
Common stock, $.01 par value; 570,000 authorized 197,080 issued and 134,573 outstanding in 2012 193,469 issued and 141,172 outstanding in 2011	1,971,000					1,935,000					1,971,000	1,935,000
Treasury stock, at cost; 62,507 in 2012; 52,297 in 2011	(1,920,749,000)					(1,583,313,000)					(1,920,749,000)	(1,583,313,000)
Additional paid-in capital	1,970,877,000					1,848,995,000					1,970,877,000	1,848,995,000
Accumulated other comprehensive income, net	69,220,000					60,469,000					69,220,000	60,469,000
Retained earnings	4,601,596,000					4,182,905,000					4,601,596,000	4,182,905,000
Total stockholders’ equity	4,722,915,000					4,510,991,000					4,722,915,000	4,510,991,000	4,199,166,000	3,712,554,000
Total liabilities and stockholders’ equity	8,750,988,000					8,813,532,000					8,750,988,000	8,813,532,000
Common stock, par value (in dollars per share)	$ 0.01					$ 0.01					$ 0.01	$ 0.01
Common stock, authorized (in shares)	570,000					570,000					570,000	570,000
Common stock, issued (in shares)	197,080					193,469					197,080	193,469
Common stock, outstanding (in shares)	134,573					141,172					134,573	141,172
Treasury stock, at cost (in shares)	62,507					52,297					62,507	52,297
Expenses:
Selling, general and administrative											2,080,236,000	2,016,042,000	1,961,947,000
Depreciation and amortization											152,859,000	136,865,000	140,685,000
Interest expense											99,468,000	99,062,000	80,418,000
(Provision) benefit for income taxes											(297,472,000)	(314,996,000)	(247,918,000)
Net earnings	119,341,000	105,259,000	91,743,000	170,719,000	[1]	85,696,000	122,681,000	224,495,000	[2]	110,233,000	487,063,000	543,105,000	438,616,000
Other comprehensive income (loss), net of tax:
Change in net unrealized gains (losses) on investments											54,626,000	48,274,000	10,501,000
Comprehensive income											495,814,000	562,493,000	438,291,000
CONDENSED STATEMENTS OF CASH FLOWS [Abstract]
Net cash from operating activities											470,644,000	401,159,000	272,252,000
Cash flows from investing activities:
Capital expenditures, net											(89,064,000)	(62,085,000)	(63,257,000)
Purchases of investments and other											(1,595,596,000)	(2,584,935,000)	(819,808,000)
Payments for acquisitions, net											(54,945,000)	(7,616,000)	(102,356,000)
Net cash from investing activities											(124,948,000)	(602,006,000)	149,661,000
Cash flows from financing activities:
Proceeds from issuance of stock											87,671,000	44,624,000	15,484,000
Payments for repurchase of stock											(339,985,000)	(336,219,000)	(4,888,000)
Repayment of debt											(233,903,000)	(380,029,000)	0
Proceeds from issuance of debt											0	589,867,000	0
Excess tax benefit from stock compensation											12,210,000	7,619,000	2,925,000
Payments for cash dividends											(51,530,000)	0	0
Net cash from financing activities											(525,537,000)	(74,138,000)	13,521,000
Net change in cash and cash equivalents											(179,841,000)	(274,985,000)	435,434,000
Cash and cash equivalents at beginning of period				1,579,003,000						1,853,988,000	1,579,003,000	1,853,988,000	1,418,554,000
Cash and cash equivalents at end of period	1,399,162,000					1,579,003,000					1,399,162,000	1,579,003,000	1,853,988,000
Subsidiary Transactions [Abstract]
Dividends from subsidiaries											214,700,000
Parent Company [Member]
Current assets:
Cash and cash equivalents	321,166,000					634,592,000					321,166,000	634,592,000	814,811,000
Short-term investments	84,241,000					61,435,000					84,241,000	61,435,000
Other receivables, net	14,394,000					4,570,000					14,394,000	4,570,000
Other current assets	41,973,000					79,923,000					41,973,000	79,923,000
Total current assets	461,774,000					780,520,000					461,774,000	780,520,000
Long-term investments	509,421,000					504,022,000					509,421,000	504,022,000
Property and equipment, net	3,574,000					4,339,000					3,574,000	4,339,000
Investment in subsidiaries	5,507,880,000					5,123,007,000					5,507,880,000	5,123,007,000
Other long-term assets	62,894,000					93,444,000					62,894,000	93,444,000
Total assets	6,545,543,000					6,505,332,000					6,545,543,000	6,505,332,000
Current liabilities:
Accounts payable and other accrued liabilities	119,617,000					315,175,000					119,617,000	315,175,000
Total current liabilities	119,617,000					315,175,000					119,617,000	315,175,000
Long-term debt	1,585,190,000					1,584,700,000					1,585,190,000	1,584,700,000
Notes payable to subsidiary	65,000,000					65,000,000					65,000,000	65,000,000
Other long-term liabilities	52,821,000					29,466,000					52,821,000	29,466,000
Total liabilities	1,822,628,000					1,994,341,000					1,822,628,000	1,994,341,000
Stockholders’ equity:
Common stock, $.01 par value; 570,000 authorized 197,080 issued and 134,573 outstanding in 2012 193,469 issued and 141,172 outstanding in 2011	1,971,000					1,935,000					1,971,000	1,935,000
Treasury stock, at cost; 62,507 in 2012; 52,297 in 2011	(1,920,749,000)					(1,583,313,000)					(1,920,749,000)	(1,583,313,000)
Additional paid-in capital	1,970,877,000					1,848,995,000					1,970,877,000	1,848,995,000
Accumulated other comprehensive income, net	69,220,000					60,469,000					69,220,000	60,469,000
Retained earnings	4,601,596,000					4,182,905,000					4,601,596,000	4,182,905,000
Total stockholders’ equity	4,722,915,000					4,510,991,000					4,722,915,000	4,510,991,000
Total liabilities and stockholders’ equity	6,545,543,000					6,505,332,000					6,545,543,000	6,505,332,000
Common stock, par value (in dollars per share)	$ 0.01					$ 0.01					$ 0.01	$ 0.01
Common stock, authorized (in shares)	570,000					570,000					570,000	570,000
Common stock, issued (in shares)	197,080					193,469					197,080	193,469
Common stock, outstanding (in shares)	134,573					141,172					134,573	141,172
Treasury stock, at cost (in shares)	62,507					52,297					62,507	52,297
Revenues:
Management fees charged to operating subsidiaries											302,718,000	261,798,000	208,453,000
Expenses:
Selling, general and administrative											198,665,000	200,005,000	170,524,000
Depreciation and amortization											575,000	1,297,000	939,000
Interest expense											101,576,000	101,174,000	82,590,000
Total expenses											300,816,000	302,476,000	254,053,000
Investment and other income, net											6,256,000	2,353,000	629,000
Income (loss) before income taxes and equity in net earnings of subsidiaries											8,158,000	(38,325,000)	(44,971,000)
(Provision) benefit for income taxes											(3,093,000)	14,069,000	16,239,000
Income (loss) before equity in net earnings of subsidiaries											5,065,000	(24,256,000)	(28,732,000)
Equity in net earnings of subsidiaries											481,998,000	567,361,000	467,348,000
Net earnings											487,063,000	543,105,000	438,616,000
Other comprehensive income (loss), net of tax:
Change in net unrealized gains (losses) on investments											8,751,000	19,388,000	(325,000)
Comprehensive income											495,814,000	562,493,000	438,291,000
CONDENSED STATEMENTS OF CASH FLOWS [Abstract]
Net cash from operating activities											84,340,000	(170,263,000)	(21,032,000)
Cash flows from investing activities:
Capital expenditures, net											444,000	(2,414,000)	518,000
Proceeds from the sales and maturities of investments											432,627,000	624,559,000	196,052,000
Purchases of investments and other											(435,100,000)	(1,155,558,000)	0
Capital contributions to subsidiaries											(134,000,000)	(140,192,000)	(142,271,000)
Dividends from subsidiaries											265,175,000	745,403,000	530,589,000
Payments for acquisitions, net											(1,375,000)	(7,616,000)	(102,356,000)
Net cash from investing activities											127,771,000	64,182,000	482,532,000
Cash flows from financing activities:
Proceeds from issuance of stock											87,671,000	44,624,000	15,484,000
Payments for repurchase of stock											(339,985,000)	(336,219,000)	(4,888,000)
Repayment of debt											(233,903,000)	(380,029,000)	0
Repayment of note to subsidiaries											0	0	(4,235,000)
Proceeds from issuance of debt											0	589,867,000	0
Excess tax benefit from stock compensation											12,210,000	7,619,000	2,925,000
Payments for cash dividends											(51,530,000)	0	0
Net cash from financing activities											(525,537,000)	(74,138,000)	9,286,000
Net change in cash and cash equivalents											(313,426,000)	(180,219,000)	470,786,000
Cash and cash equivalents at beginning of period				634,592,000						814,811,000	634,592,000	814,811,000	344,025,000
Cash and cash equivalents at end of period	321,166,000					634,592,000					321,166,000	634,592,000	814,811,000
Subsidiary Transactions [Abstract]
Dividends from subsidiaries											214,700,000	489,400,000	319,400,000
Capital Contributions From Parent Co											$ 134,000,000	$ 122,000,000	$ 11,500,000

[1] During the quarter ended March 31, 2012, CMS announced which contract years are subject to the CMS RADV audits and other core areas of the audit methodology. As a result of these changes, the Company recorded a non-recurring pre-tax adjustment to earnings of $133.0 million during the first quarter of 2012. See Note A, Organization and Summary of Significant Accounting Policies, to the consolidated financial statements for additional information.

[2] On May 27, 2011, the court entered an order of final approval of a settlement and, accordingly, the Company recorded a non-recurring pre-tax adjustment that increased earnings of $159.3 million in the second quarter of 2011.