Securities (Gains and Losses Recognized in Income from Trading Securities) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Trading Securities And Other Trading Assets
Realized gains	[1]	$ 2	$ 1	$ 7	$ 4
Realized losses	[2]	2	2	8	7
Net unrealized gains (losses)	[3]	2	(3)	3	(4)
Corporate Banking Revenue and Wealth and Asset Management Revenue
Schedule Of Trading Securities And Other Trading Assets
Realized gains		1	1	6	3
Realized losses		$ (1)	$ (2)	$ (7)	$ (7)

[1] Includes realized gains of $ 1 and $ 6 for the three and nine months ended September 30, 2016 , respectively, and $ 1 and $ 3 for the three and nine months ended September 30, 2015 , respectively, recorded in corporate banking revenue and wealth and asset management revenue in the Condensed Consolidated Statements of Income.

[2] Includes realized losses of $ 1 and $ 7 for the three and nine months ended September 30, 2016 , respectively, and $ 2 and $ 7 for the three and nine months ended September 30, 2015 , respec tively, recorded in corporate banking revenue and wealth and asset management revenue in the Condensed Consolidated Statements of Income.

[3] Include s an immaterial amount of net unrealized losses during the three months ended September 30, 2016 and an immaterial am ount of net unrealized gains during the nine months ended September 30, 2016 and the three and nine months ended September 30, 2015 , recorded in corporate banking revenue and wealth and asset management revenue in the Condensed Consolidated Statements of I ncome.