MSR (Activity Related to Mortgage Banking Net Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	[1]	$ 1,474	$ 1,518	$ 2,474	$ 3,147
Origination fees and gains on loan sales		28	37	52	66
Gross Mortgage Servicing Fees		$ 54	$ 49	$ 106	$ 97

[1] Represents the unpaid principal balance at the time of the sale.