MSR (Activity Related to Mortgage Banking Net Revenue) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	[1]	$ 6,369	$ 6,927	[2]	$ 5,078
Origination fees and gains on loan sales		138	186		171
Gross mortgage servicing fees		$ 206	$ 199		$ 222

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

[2] Excludes $ 568 of HFS residential mortgage loans previously modified in a TDR that were sold d uring the first quarter of 2015.