Stock-Based Compensation Expense Recognized in Noninterest Expense (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Document Period End Date				Sep. 30, 2017
Stock-based compensation expense:
Stock or Unit Option Plan Expense		$ 14	$ 13	$ 64	$ 44
Restricted Stock or Unit Expense		0	0	0	2
Performance Stock Units	[1]	17	16	57	39
Share-based Compensation		31	29	121	85
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	[2]	$ 12	$ 11	$ 46	$ 32

[1] Phantom stock units are settled in cash.

[2] Does not include excess tax benefits or deficiencies recognized in the Provision for income taxes in the Consolidated Statements of Income.