Global Health Care Medical Claims Payable (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Paid claims related to:
Ending balance, net	$ 4,161		$ 4,062
Add: Reinsurance and other amounts recoverable	7,407		6,256
Accident and Health Insurance Segment [Member]
Schedule Of Reported and Incurred but not Reported (IBNR) Medical Claims Payable (Details) [Abstract]
Incurred but not yet reported	1,666		1,541
Reported claims in process	222		243
Physician incentives and other medical expense payable	115		72
Medical claims payable	2,003		1,856
Schedule Of Medical Claims Payable Activity [Abstract]
Claims payable, beginning balance, gross	1,856	1,305	1,305
Less: Reinsurance and other amounts recoverable	242	249	249
Balance at January 1, net	1,614	1,056	1,056
Acquired net:	0		504
Incurred claims related to:
Current year	8,109		14,428
Prior years	(158)		(200)
Total incurred	7,951		14,228
Paid claims related to:
Current year	6,458		12,854
Prior years	1,290		1,320
Total paid	7,748		14,174
Ending balance, net	1,817		1,614
Add: Reinsurance and other amounts recoverable	186		242
Claims payable, ending balance, gross	2,003		1,856
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	(158)		(200)
Incurred claims related to prior years' claims payable percentage	1.10%		2.20%
Favorable (Unfavorable) Impact Of Prior Year Development On Shareholders Net Income	68	58
Completion Factors [Member] | Accident and Health Insurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	(66)		(91)
Incurred claims related to prior years' claims payable percentage	0.50%		1.00%
Medical Cost Trend [Member] | Accident and Health Insurance Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	$ (92)		$ (109)
Incurred claims related to prior years' claims payable percentage	0.60%		1.20%