MSR (Activity Related to the MSR Portfolio) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Servicing Assets at Fair Value
Recovery of (provision for) MSR impairment (Mortgage banking net revenue)	$ 0	$ (85)	[1]
MSR Fair Value Adjustment	23	0	[1]
Interest Rate Contract | Servicing Rights | Mortgage Banking Revenue
Servicing Assets at Fair Value
Changes in fair value and settlement of free-standing derivatives purchased to economically hedge the MSR portfolio (Mortgage banking net revenue)	$ (1)	$ 96

[1] A net tax deficiency of $ 1 million was reclassified from capital surplus to applicable income tax expense at March 31, 2016, related to the early adoption of ASU 2016-09 during the fourth quarter of 2016, with an effective date of January 1, 2016.