Securities-Pre-Tax Net Securities Gains (Losses) by Type (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	$ 20	$ 18	$ 22	$ 60	$ 102
State and political subdivisions
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	7	7	0	13	0
U.S. Treasury
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	1	1	22	12	49
U.S. Government agencies
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	0	0	0	7	0
Foreign covered bonds
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	0	3	0	3	8
European floating rate notes
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	2	0	3	1	(3)
Commercial MBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	1	0	0	1	15
Non-agency RMBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	4	(2)	(4)	0	(3)
Other securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net securities gains	$ 5	$ 9	$ 1	$ 23	$ 36