MSR (Activity Related to Mortgage Banking Net Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	[1]	$ 1,162	$ 1,000
Origination fees and gains on loan sales		25	24
Gross mortgage servicing fees		$ 55	$ 53

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