Health Care Medical Claims Payable (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Health Care Medical Claims Payable Text Details [Abstract]
Difference in experience from assumptions, medical claims payable			$ (162)		$ (126)
Percent difference in experience from assumptions, medical claims payable			2.00%		1.50%
Difference in completion factors, medical claims payable			(69)		(87)
Percent difference in completion factors, medical claims payable			0.80%		1.00%
Difference in medical cost trend, medical claims payable			(93)		(39)
Percent difference in medical cost trend, medical claims payable			1.10%		0.50%
After Tax Impact Of Prior Year Development On Shareholders Net Income			55	47
Schedule Of Medical Claims Payable Activity Details [Abstract]
Balance at January 1,			1,095	1,246	1,246
Less: Reinsurance and other amounts recoverable			194	236	236
Balance at January 1, net			901	1,010	1,010
Acquired HealthSpring balances, net			504		0
Incurred Claims Details [Abstract]
Current year			6,604		8,308
Prior years			(162)		(126)
Total incurred	3,405	2,034	6,442	4,111	8,182
Paid Claims Details [Abstract]
Current year			5,248		7,450
Prior years			1,099		841
Total paid			6,347		8,291
Ending Balance, net	1,500		1,500		901
Add: Reinsurance and other amounts recoverable	207		207		194
Medical claims payable	1,707		1,707		1,095
Schedule Of Medical Claims Payable Details [Abstract]
Incurred but not yet reported			1,399		952
Reported claims in process	195		195		129
Physician's Incentives and other medical expense payable	113		113		14
Medical claims payable	$ 1,707		$ 1,707		$ 1,095