Investments (Credit Losses Recognized In Earnings Related To OTTI Losses Recognized In Accumulated Other Comprehensive Income (Loss)) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Beginning balance	$ 341		$ 262	$ 389
Accounting transition adjustment				(149)	[1]
Additions for credit loss impairments recognized in the current period on securities not previously impaired			63	24
Additions for credit loss impairments recognized in the current period on securities previously impaired	8		31	18
Additions for credit loss impairments recognized in prior periods for securities that were re-impaired with a non-credit component in the current period				1
Reductions for credit loss impairments previously recognized on securities sold during the period	(41)		(15)	(16)
Reductions for credit loss impairments previously recognized on securities impaired to fair value during the period	(111)	[2]		(4)	[2]
Reductions for increases in cash flows expected to be collected over the remaining life of the security				(1)
Ending balance	$ 197		$ 341	$ 262

[1] Reflects the adoption of the accounting principles for the consolidation of VIEs.

[2] Represents circumstances where the Company determined in the current period that it intends to sell the security or it is more likely than not that it will be required to sell the security before recovery of the security's amortized cost.