MSR (Activity Related to the MSR Portfolio) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Servicing Assets at Fair Value
Securities gains, net - non-qualifying hedges on mortgage servcing rights		$ 2	$ 0	$ 4	$ 0
MSR Fair Value Adjustment	[1]			104	0	[2]
Recovery of (provision for) MSR impairment (Mortgage banking net revenue)	[1]			0	(125)	[2]
Mortgage Banking Revenue
Servicing Assets at Fair Value
MSR Fair Value Adjustment		(34)	0	(104)	0
Recovery of (provision for) MSR impairment (Mortgage banking net revenue)		0	(7)	0	125
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]	$ 1	$ (16)	$ 16	$ 133

[1] (a) Included in mortgage banking net revenue in the Condensed Consolidated Statements of Income.

[2] Net tax deficiencies of $ 6 were reclassified from capital surplus to applicable income tax expense for the nine months ended September 30, 2016, related to the early adoption of ASU 2016-09 during the fourth quarter of 2016, with an effective date of January 1, 2016.