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			9 Months Ended
	Sep. 30, 2022		Sep. 30, 2021	Sep. 30, 2022		Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,014		$ 2,033	$ 1,892	[1]	$ 2,453
Losses charged-off	(104)		(56)	(259)		(268)
Recoveries of losses previously charged-off	42		35	100		132
(Benefit from) provision for loan and lease losses	147		(58)	366		(363)
Balance, end of period	2,099	[1]	1,954	2,099	[1]	1,954
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged-off	(8)		(7)	(23)		(25)
Recoveries of losses previously charged-off	8		7	23		25
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,165		1,224	1,102		1,456
Losses charged-off	(47)		(10)	(95)		(91)
Recoveries of losses previously charged-off	15		6	19		40
(Benefit from) provision for loan and lease losses	25		(53)	132		(238)
Balance, end of period	1,158		1,167	1,158		1,167
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	248		235	235		294
Losses charged-off	(1)		(1)	(2)		(3)
Recoveries of losses previously charged-off	2		2	4		5
(Benefit from) provision for loan and lease losses	5		(1)	17		(61)
Balance, end of period	254		235	254		235
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	601		574	555		703
Losses charged-off	(56)		(45)	(162)		(174)
Recoveries of losses previously charged-off	25		27	77		87
(Benefit from) provision for loan and lease losses	117		(4)	217		(64)
Balance, end of period	$ 687		$ 552	$ 687		$ 552

[1] Includes $19 and $24 of other short-term investments, $223 and $322 of portfolio loans and leases, $(3) and $(2) of ALLL, $2 and $2 of other assets, $9 and $1 of other liabilities, and $156 and $263 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2022 and December 31, 2021, respectively. For further information, refer to Note 12.