MSR - Activity Related to Mortgage Banking Net Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	$ 1,654	$ 1,474	$ 2,815	$ 2,474
Origination fees and gains on loan sales	37	28	62	52
Gross mortgage servicing fees	$ 70	$ 54	$ 125	$ 106