Global Health Care Medical Claims Payable (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Paid claims related to:
Balance at December 31, net	$ 4,062	$ 3,936
Add: Reinsurance and other amounts recoverable	6,256	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	1,541	1,059
Reported claims in process	243	232
Other medical expense payable	72	14
Medical claims payable	1,856	1,305
Schedule Of Medical Claims Payable Activity [Abstract]
Claims payable, beginning balance, gross	1,305	1,400	1,045
Less: Reinsurance and other amounts recoverable	249	284	257
Balance at January 1, net	1,056	1,116	788
Acquired net:	504	0	0
Incurred claims related to:
Current year	14,428	9,265	9,337
Prior years	(200)	(140)	(115)
Total incurred	14,228	9,125	9,222
Paid claims related to:
Current year	12,854	8,227	8,217
Prior years	1,320	958	677
Total paid	14,174	9,185	8,894
Balance at December 31, net	1,614	1,056	1,116
Add: Reinsurance and other amounts recoverable	242	249	284
Claims payable, ending balance, gross	1,856	1,305	1,400
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	(200)	(140)
Incurred claims related to prior years' claims payable percentage	2.20%	1.50%
Impact Of Prior Year Development On Shareholders Net Income	66	49
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	(91)	(96)
Incurred claims related to prior years' claims payable percentage	1.00%	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	$ (109)	$ (44)
Incurred claims related to prior years' claims payable percentage	1.20%	0.50%