Credit Quality and the Allowance for Loan and Lease Losses - Summary of Transactions in the ALLL by Portfolio Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,194	[1]	$ 1,892		$ 2,453
Losses charged off	(522)		(362)		(344)
Recoveries of losses previously charged off	134		135		170
Provision for (benefit from) loan and lease losses	565		529		(387)
Balance, end of period	2,322	[1]	$ 2,194	[1]	1,892
Accounting Standards Update [Extensible List]			Accounting Standards Update 2022-02
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged off	(35)		$ (32)		(33)
Recoveries of losses previously charged off	35		32		33
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	(49)
Balance, end of period			(49)
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,127		1,102		1,456
Losses charged off	(170)		(131)		(119)
Recoveries of losses previously charged off	17		30		52
Provision for (benefit from) loan and lease losses	152		126		(287)
Balance, end of period	1,130		1,127		1,102
Commercial | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	4
Balance, end of period			4
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	245		235		294
Losses charged off	(4)		(3)		(3)
Recoveries of losses previously charged off	4		5		7
Provision for (benefit from) loan and lease losses	(64)		8		(63)
Balance, end of period	145		245		235
Residential Mortgage | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	(36)
Balance, end of period			(36)
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	822		555		703
Losses charged off	(348)		(228)		(222)
Recoveries of losses previously charged off	113		100		111
Provision for (benefit from) loan and lease losses	477		395		(37)
Balance, end of period	1,047		822		$ 555
Consumer | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ (17)
Balance, end of period			$ (17)

[1] Includes $55 and $17 of other short-term investments, $1,573 and $185 of portfolio loans and leases, $(28) and $(2) of ALLL, $10 and $2 of other assets, $14 and $9 of other liabilities and $1,409 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2023 and 2022, respectively. For further information, refer to Note 12.