MSR (Activity Related to Mortgage Banking Net Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	[1]	$ 1,629	$ 1,114
Origination fees and gains on loan sales		29	42
Gross Mortgage Servicing Fees		$ 47	$ 52

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