Goodwill and Mortgage Servicing Rights - Mortgage Servicing Rights (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Mortgage Servicing Rights [Roll Forward]
Fair value at beginning of period	$ 5,494	$ 3,276
MSR activity:
Originations of MSRs	415	404
Purchase of MSRs	715	179
Disposition of MSRs	(57)	1
Net additions/(dispositions)	1,073	584
Changes due to collection/realization of expected cash flows	(232)	(187)
Changes in valuation due to inputs and assumptions:
Changes due to market interest rates and other	894	836
Changes in valuation due to other inputs and assumptions:
Projected cash flows (e.g., cost to service)	0	(24)
Discount rates	0	0
Prepayment model changes and other	65	(15)
Total changes in valuation due to other inputs and assumptions	65	(39)
Total changes in valuation due to inputs and assumptions	959	797
Fair value at end of period	7,294	4,470
Changes in unrealized gains/(losses) included in income related to MSRs	959	797
Contractual service fees, late fees and other ancillary fees included in income	370	291
Third-party mortgage loans serviced	576,000	444,000
Servicer advances, net of an allowance for uncollectible amounts	$ 1,400	$ 1,800