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			12 Months Ended
	Sep. 30, 2023		Sep. 30, 2022	Sep. 30, 2023		Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,327		$ 2,014	$ 2,194	[1]	$ 1,892	$ 1,892
Losses charged off	(158)		(104)	(389)		(259)
Recoveries of losses previously charged off	34		42	97		100
Provision for (benefit from) loan and lease losses	137		147	487		366
Balance, end of period	2,340	[1]	2,099	2,340	[1]	2,099	$ 2,194	[1]
Accounting Standards Update [Extensible Enumeration]							Accounting Standards Update 2022-02
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged off	(8)		(8)	(26)		(23)
Recoveries of losses previously charged off	8		8	26		23
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	1,199		1,165	1,127		1,102	1,102
Losses charged off	(70)		(47)	(140)		(95)
Recoveries of losses previously charged off	6		15	13		19
Provision for (benefit from) loan and lease losses	52		25	183		132
Balance, end of period	1,187		1,158	1,187		1,158	1,127
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	173		248	245		235	235
Losses charged off	(1)		(1)	(3)		(2)
Recoveries of losses previously charged off	1		2	3		4
Provision for (benefit from) loan and lease losses	(18)		5	(54)		17
Balance, end of period	155		254	155		254	245
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	955		601	822		555	555
Losses charged off	(87)		(56)	(246)		(162)
Recoveries of losses previously charged off	27		25	81		77
Provision for (benefit from) loan and lease losses	103		117	358		217
Balance, end of period	$ 998		$ 687	998		$ 687	822
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 $59 and $17 of other short-term investments, $1,728 and $185 of portfolio loans and leases, $(27) and $(2) of ALLL, $11 and $2 of other assets, $15 and $9 of other liabilities, and $1,553 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2023 and December 31, 2022, respectively. For further information, refer to Note 12.