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, 2024		Dec. 31, 2023		Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,322	[1]	$ 2,194		$ 1,892
Losses charged off	(686)		(522)		(362)
Recoveries previously charged off	154		134		135
Provision for (benefit from) loan and lease losses	562		565		529
Balance, end of period	2,352	[1]	2,322	[1]	$ 2,194
Accounting Standards Update [Extensible Enumeration]					Accounting Standards Update 2022-02 [Member]
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged off	(28)		(35)		$ (32)
Recoveries previously charged off	28		35		32
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	1,130		1,127		1,102
Losses charged off	(267)		(170)		(131)
Recoveries previously charged off	23		17		30
Provision for (benefit from) loan and lease losses	268		152		126
Balance, end of period	1,154		1,130		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	145		245		235
Losses charged off	(2)		(4)		(3)
Recoveries previously charged off	4		4		5
Provision for (benefit from) loan and lease losses	(1)		(64)		8
Balance, end of period	146		145		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	1,047		822		555
Losses charged off	(417)		(348)		(228)
Recoveries previously charged off	127		113		100
Provision for (benefit from) loan and lease losses	295		477		395
Balance, end of period	$ 1,052		1,047		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 $51 and $55 of other short-term investments, $1,000 and $1,573 of portfolio loans and leases, $(19) and $(28) of ALLL, $5 and $10 of other assets, $12 and $14 of other liabilities and $889 and $1,409 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2024 and 2023, respectively. For further information, refer to Note 12.