Loan Servicing - Analysis of Activity in Residential MSRs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Servicing Asset at Fair Value, Amount [Roll Forward]
MSRs, carrying value, beginning balance	$ 1,108
Change in fair value due to changes in valuation inputs or assumptions:
MSRs, carrying value, ending balance	2,618	$ 1,108
Residential MSRs
Servicing Asset at Fair Value, Amount [Roll Forward]
MSRs, carrying value, beginning balance	957	914	$ 915
Other additions	171	116	123
Change in fair value due to changes in valuation inputs or assumptions:
Prepayment speeds	(131)	(12)	(42)
OAS	32	57	46
Servicing costs	0	22	9
Realization of expected net servicing cash flows, passage of time and other	(164)	(140)	(137)
MSRs, carrying value, ending balance	2,371	957	914
Residential MSRs | SunTrust Banks Inc.
Servicing Asset at Fair Value, Amount [Roll Forward]
Other additions	$ 1,506	$ 0	$ 0