Securities (Realized Gains and Losses Recognized in Income from Available-for-Sale Securities) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Investments, Unrealized Loss Position
OTTI	[1]	$ (2)	$ 0	$ (8)	$ (5)
Available-for-sale Securities
Investments, Unrealized Loss Position
Realized gains		13	35	42	79
Realized losses		(9)	(25)	(16)	(58)
OTTI		(2)	0	(8)	(5)
Net realized gains (losses)	[2]	$ 2	$ 10	$ 18	$ 16

[1] (a) Included in securities gains, net, in the Condensed Consolidated Statements of Income.

[2] (a) Excludes n et gains on interest-only mortgage- backed securities of an immaterial amount and net losses of $ 8 for the three and nine months ended September 30, 2016 , respectively, and net losses on interest-onl y mortgage-backed securities of $ 7 and $ 4 for the three and nine months ended September 30, 2015 , respectively.