Gross Realized Gains and Losses on Sales and OTTI on Securities Available for Sale (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Gross realized gains	$ 1		$ 16		$ 4		$ 36
Available-for-sale Securities, Gross Realized Losses	(1)		0		(1)		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	0		(2)		(1)		(4)
Gain (Loss) on Sale of Securities, Net	$ 0	[1]	$ 14	[2]	$ 2	[2]	$ 32	[2]

[1] Includes OTTI securities for which credit losses have been recorded in earnings in current or prior periods.

[2] Includes credit-related OTTI losses of $0 and $2 million that were unrealized losses reclassified from OCI, before taxes, for the three months ended June 30, 2013 and 2012, respectively, and $1 million and $4 million that were unrealized losses reclassified from OCI, before taxes, for the six months ended June 30, 2013 and 2012, respectively.