Gains and Losses Recognized in Income from Trading Securities (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Realized gains	[1]	$ 6	$ 8	$ 5
Realized losses	[2]	10	7	8
Net unrealized gains (losses)	[3]	(3)	(3)	3
Corporate Banking Revenue and Investment Advisory Revenue
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Realized gains		6	4	4
Realized losses		$ (10)	$ (7)	$ (8)

[1] Includes realized gains of $6, $4 and $4 for the years ended December 31, 2015, 2014 and 2013, respectively, recorded in corporate banking revenue and investment advisory revenue in the Consolidated Statements of Income.

[2] Includes realized losses of $10, $7 and $8 for the years ended December 31, 2015, 2014 and 2013, respectively, recorded in corporate banking revenue and investment advisory revenue in the Consolidated Statements of Income.

[3] Includes an immaterial amount of net unrealized gains for the years ended December 31, 2015, 2014 and 2013 recorded in corporate banking revenue and investment advisory revenue in the Consolidated Statements of Income.