Gains and Losses Recognized in Income from Trading Securities (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Realized gains	[1]	$ 2	$ 1
Realized losses	[2]	4	3
Net unrealized gains (losses)	[3]	1	1
Corporate Banking Revenue and Investment Advisory Revenue
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Realized gains		2	1
Realized losses		$ (4)	$ (3)

[1] Includes realized gains of $2 and $1 during the three months ended March 31, 2016 and 2015, respectively, recorded in corporate banking revenue and investment advisory revenue in the Condensed Consolidated Statements of Income.

[2] Includes realized losses of $4 and $3 during the three months ended March 31, 2016 and 2015, respectively, recorded in corporate banking revenue and investment advisory revenue in the Condensed Consolidated Statements of Income.

[3] Includes an immaterial amount of net unrealized gains and losses during the three months ended March 31, 2016 and 2015, respectively, recorded in corporate banking revenue and investment advisory revenue in the Condensed Consolidated Statements of Income.