Stock-Based Compensation Expense Recognized in Noninterest Expense (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Document Period End Date		Mar. 31, 2017
Stock-based compensation expense:
Stock or Unit Option Plan Expense		$ 34	$ 18
Restricted Stock or Unit Expense		0	2
Performance Stock Units	[1]	24	7
Share-based Compensation		58	27
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options		$ 22	$ 10

[1] Phantom stock units are settled in cash.