Securities (Gains and Losses Recognized in Income from Trading Securities) (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Trading Securities And Other Trading Assets
Realized gains	[1]	$ 9	$ 6	$ 8
Realized losses	[2]	13	10	7
Net unrealized gains (losses)	[3]	4	(3)	(3)
Corporate Banking Revenue and Wealth and Asset Management Revenue
Schedule Of Trading Securities And Other Trading Assets
Realized gains		7	6	4
Realized losses		$ (10)	$ (10)	$ (7)

[1] Includes realized gains of $ 7 , $ 6 and $ 4 for the years ended December 31, 2016 , 2015 and 2014 , respectively, recorded in corporate banking revenue and wealth and asset management revenue in the Consolidated Statements of Income.

[2] Includes realized losses of $ 10 , $ 10 and $ 7 for the years ended December 31, 2016 , 2015 and 2014 , respectively, recorded in corporate banking revenue and wealth and asset management revenue in the Consolidated Statements of Income.

[3] Includes an immaterial amount of net unrealized gains for the years ended December 31, 2016 and 2015 , respectively, and an immaterial amount of net unrealized losses for the year ended 2014 recorded in corporate banking revenue and wealth and asset management revenue in the Consolidated Statements of Income.