Credit Quality and the Allowance for Loan and Lease Losses - Summary of Transactions in the ALLL by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022		Mar. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 1,892	[1]	$ 2,453
Losses charged-off	(64)		(109)
Recoveries of losses previously charged-off	30		38
(Benefit from) provision for loan and lease losses	50		(174)
Balance, end of period	1,908	[1]	2,208
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged-off	(8)		(10)
Recoveries of losses previously charged-off	8		10
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,102		1,456
Losses charged-off	(11)		(35)
Recoveries of losses previously charged-off	3		7
(Benefit from) provision for loan and lease losses	16		(99)
Balance, end of period	1,110		1,329
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	235		294
Losses charged-off	(1)		(1)
Recoveries of losses previously charged-off	2		1
(Benefit from) provision for loan and lease losses	3		(47)
Balance, end of period	239		247
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	555		703
Losses charged-off	(52)		(73)
Recoveries of losses previously charged-off	25		30
(Benefit from) provision for loan and lease losses	31		(28)
Balance, end of period	$ 559		$ 632

[1] Includes $24 and $24 of other short-term investments, $266 and $322 of portfolio loans and leases, $(2) and $(2) of ALLL, $2 and $2 of other assets, an immaterial amount and $1 of other liabilities, and $209 and $263 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2022 and December 31, 2021, respectively. For further information, refer to Note 11.