Securities-Pre-Tax Net Securities Gains (Losses) by Type (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	$ 48	$ 50	$ 40
Foreign covered bonds
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	8	0	0
Commercial MBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	8	0	0
European floating rate notes
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	4	(5)	(1)
Non-Agency RMBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	4	(24)	(14)
Sovereign Debt
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	1	13	7
Agency RMBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	0	43	0
Corporate bonds
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	0	10	2
FDIC-insured debt
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	0	0	10
U.S. Treasury
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	(4)	1	38
Other securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net Securities Gain Loss	$ 27	$ 12	$ (2)