MSR - Activity Related to Mortgage Banking Net Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	$ 2,397	$ 1,446	$ 5,212	$ 3,919
Origination fees and gains on loan sales	64	25	126	77
Gross mortgage servicing fees	$ 71	$ 56	$ 196	$ 162