Claim and Claim Adjustment Expense Reserves (Reconcilliation of claim and claim adjustment expense reserves) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Reserves, beginning of year:
Gross	$ 24,303		$ 25,496		$ 26,816
Ceded	5,020		6,122		5,594
Net reserves, beginning of year	19,283		19,374		21,222
Reduction of net reserves due to the Loss Portfolio Transfer transaction					(1,381)
Change in net reserves due to acquisition (disposition) of subsidiaries	291		(277)		(98)
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	5,273		4,904		4,741
Increase (decrease) in provision for insured events of prior years	(182)		(429)		(544)
Amortization of discount	145		135		123
Total net incurred (a)	(5,236)	[1]	(4,610)	[1]	(4,320)	[1]
Net payments attributable to:
Current year events	(988)		(1,029)		(908)
Prior year events	(4,280)		(3,473)		(3,776)
Total net payments	(5,268)		(4,502)		(4,684)
Foreign currency translation adjustment and other	95		78		(5)
Net reserves, end of year	19,637		19,283		19,374
Ceded reserves, end of year	5,126		5,020		6,122
Gross reserves, end of year	$ 24,763		$ 24,303		$ 25,496

[1] Total net incurred above does not agree to Insurance claims and policyholders' benefits as reflected on the Consolidated Statements of Operations due to amounts related to uncollectible reinsurance and loss deductible receivables, and benefit expenses related to future policy benefits and policyholders' funds, which are not reflected in the table above.