Securities-Pre-Tax Net Securities Gains (Losses) by Type (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	$ 22	$ 32	$ 22	$ 102	$ 112
U.S. Treasury
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	22	31	0	49	82
Commercial MBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	0	7	0	15	0
Foreign covered bonds
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	0	0	0	8	0
Non-agency RMBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	1	0	15	2	83
Non-Agency Residential Mortgage Backed Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	(4)	(3)	(3)	(3)	(44)
European floating rate notes
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	3	(10)	(6)	(3)	(29)
Corporate Bond Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	0	0	10	0	19
Other securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	$ 0	$ 7	$ 6	$ 34	$ 1