Securities (Gains and Losses Recognized in Income from Trading Securities) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Trading Securities And Other Trading Assets
Realized gains	[1]	$ 2	$ 4	$ 5	$ 5
Realized losses	[2]	2	2	4	6
Net unrealized gains (losses)	[3]	4	1	5	1
Corporate Banking Revenue and Wealth and Asset Management Revenue
Schedule Of Trading Securities And Other Trading Assets
Realized gains		2	4	4	5
Realized losses		$ (2)	$ (2)	$ (4)	$ (6)

[1] Includes realized gains of $ 2 and $ 4 for the three and six months ended June 30, 2017 , respectively, and $ 4 and $ 5 for the three and six months ended June 30, 2016 , respectively, recorded in corporate banking revenue and wealth and asset management revenue in the Condensed Consolidated Statements of Income.

[2] Includes realized losses of $ 2 and $ 4 for the three and six months ended June 30, 2017 , respectively, and $ 2 and $ 6 for the three and six months ended June 30, 2016 , 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 June 30, 2017 and an immaterial am ount of net unrealized gains during the six months ended June 30, 2017 and both the three and six months ended June 30, 2016 , recorded in corporate banking revenue and wealth and asset management revenue in the Condensed Consolidated Statements of Income.