Loan Servicing - Analysis of Activity in Residential MSRs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Servicing Asset at Fair Value, Amount [Roll Forward]
MSRs, carrying value, beginning balance	$ 2,023
MSRs, carrying value, ending balance	2,633	$ 2,023
Residential MSRs
Servicing Asset at Fair Value, Amount [Roll Forward]
MSRs, carrying value, beginning balance	1,778	2,371	$ 957
Additions	640	653	171
Realization of expected net servicing cash flows, passage of time and other	(693)	(749)	(164)
MSRs, carrying value, ending balance	2,305	1,778	2,371
Change in fair value due to changes in valuation inputs or assumptions:
Prepayment speeds	(2)	(572)	(131)
OAS	227	75	32
Residential MSRs | Merger
Servicing Asset at Fair Value, Amount [Roll Forward]
Additions	$ 355	$ 0	$ 1,506