Rollforward of Credit Losses Recognized in Earnings Related to Securities (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Beginning balance	$ 31	$ 25	$ 20
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	1	7	6
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Securities Sold	(6)	0	0
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Cash Flows	(1)	(1)	(1)
Ending balance	$ 25	$ 31	$ 25