Loans - 90+ Day Delinquent Loans Accruing Interest and Nonperforming Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	$ 3,032		$ 3,032		$ 2,240
Nonperforming Loans	1,515		1,515		1,344
Nonperforming Loans Without an Allowance	$ 534		$ 534		$ 548
Percentage, 90 Days Past Due and Accruing	0.96%		0.96%		0.72%
Percentage, Nonperforming Loans	0.48%		0.48%		0.43%
Percentage, Nonperforming Loans Without an Allowance	0.17%		0.17%		0.18%
Interest income for loans classified as nonperforming	$ 11	$ 2	$ 47	$ 29
Credit Card:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	3,019		3,019		$ 2,240
Nonperforming Loans	9		9		9
Nonperforming Loans Without an Allowance	0		0		0
Credit Card: | Domestic credit card:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	2,904		2,904		2,135
Nonperforming Loans Without an Allowance	0		0		0
Credit Card: | International card businesses:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	115		115		105
Nonperforming Loans	9		9		9
Nonperforming Loans Without an Allowance	0		0		0
Consumer Banking:
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0		0
Nonperforming Loans	684		684		634
Nonperforming Loans Without an Allowance	23		23		8
Consumer Banking: | Auto
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0		0
Nonperforming Loans	639		639		595
Nonperforming Loans Without an Allowance	0		0		0
Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0		0
Nonperforming Loans	45		45		39
Nonperforming Loans Without an Allowance	23		23		8
Commercial Portfolio
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	13		13		0
Nonperforming Loans	822		822		701
Nonperforming Loans Without an Allowance	511		511		540
Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	0		0		0
Nonperforming Loans	459		459		271
Nonperforming Loans Without an Allowance	312		312		246
Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
90 Days Past Due and Accruing	13		13		0
Nonperforming Loans	363		363		430
Nonperforming Loans Without an Allowance	$ 199		$ 199		$ 294