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, 2025		Mar. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,352	[1]	$ 2,322
Losses charged off	(173)		(146)
Recoveries of losses previously charged off	37		36
Provision for (benefit from) loan and lease losses	168		106
Balance, end of period	2,384	[1]	2,318
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged off	(6)		(8)
Recoveries of losses previously charged off	6		8
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,154		1,130
Losses charged off	(67)		(40)
Recoveries of losses previously charged off	3		5
Provision for (benefit from) loan and lease losses	151		46
Balance, end of period	1,241		1,141
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	146		145
Losses charged off	0		0
Recoveries of losses previously charged off	0		0
Provision for (benefit from) loan and lease losses	(7)		(5)
Balance, end of period	139		140
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,052		1,047
Losses charged off	(106)		(106)
Recoveries of losses previously charged off	34		31
Provision for (benefit from) loan and lease losses	24		65
Balance, end of period	$ 1,004		$ 1,037

[1] Includes $47 and $51 of other short-term investments, $874 and $1,000 of portfolio loans and leases, $(16) and $(19) of ALLL, $6 and $5 of other assets, $12 and $12 of other liabilities and $774 and $889 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2025 and December 31, 2024, respectively. For further information, refer to Note 7.