Investments (Credit Losses Recognized In Earnings Related To OTTI Losses Recognized In Accumulated Other Comprehensive Income (Loss)) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Beginning balance	$ 197	$ 341
Additions for credit loss impairments recognized in the current period on securities previously impaired		2
Reductions for credit loss impairments previously recognized on securities sold during the period	(2)	(7)
Reductions for credit loss impairments previously recognized on securities impaired to fair value during the period		(59)	[1]
Ending balance	$ 195	$ 277

[1] 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.