Loans - Financing Receivable, Modified - Modification to Borrowers (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 1,183	$ 787
% of total class of receivables	0.38%	0.25%
Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 270	$ 188
Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	459	240
Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	9	7
Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		17
Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	307	202
Other
Financing Receivable, Past Due [Line Items]
Total loans modified	138	133
Credit Card:
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 275	$ 188
% of total class of receivables	0.18%	0.14%
Credit Card: | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 270	$ 188
Credit Card: | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Credit Card: | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Credit Card: | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Credit Card: | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	5	0
Credit Card: | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Credit Card: | Domestic Card
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 221	$ 150
% of total class of receivables	0.15%	0.11%
Credit Card: | Domestic Card | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 216	$ 150
Weighted-average interest rate reduction	19.99%	19.02%
Credit Card: | Domestic Card | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Payment delay duration (in months)	12 months
Credit Card: | Domestic Card | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	0
Principal balance reduction	0	0
Credit Card: | Domestic Card | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Credit Card: | Domestic Card | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	5	0
Credit Card: | Domestic Card | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Credit Card: | International card businesses
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 54	$ 38
% of total class of receivables	0.80%	0.62%
Credit Card: | International card businesses | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 54	$ 38
Weighted-average interest rate reduction	26.12%	25.74%
Credit Card: | International card businesses | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Credit Card: | International card businesses | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Principal balance reduction	0	0
Credit Card: | International card businesses | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Credit Card: | International card businesses | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Credit Card: | International card businesses | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Consumer Banking:
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 292	$ 255
% of total class of receivables	0.39%	0.33%
Consumer Banking: | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Consumer Banking: | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	8	45
Consumer Banking: | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	9	7
Consumer Banking: | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Consumer Banking: | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	274	202
Consumer Banking: | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	1	1
Consumer Banking: | Auto
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 290	$ 252
% of total class of receivables	0.39%	0.33%
Consumer Banking: | Auto | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Weighted-average interest rate reduction	8.65%	8.75%
Consumer Banking: | Auto | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 6	$ 42
Payment delay duration (in months)	6 months	6 months
Consumer Banking: | Auto | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 9	$ 7
Principal balance reduction	0	0
Consumer Banking: | Auto | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Consumer Banking: | Auto | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	274	202
Consumer Banking: | Auto | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	1	1
Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 2	$ 3
% of total class of receivables	0.14%	0.18%
Consumer Banking: | Retail banking | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Weighted-average interest rate reduction	0.00%	0.00%
Consumer Banking: | Retail banking | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 2	$ 3
Payment delay duration (in months)	10 months	14 months
Consumer Banking: | Retail banking | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Principal balance reduction	0	0
Consumer Banking: | Retail banking | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Consumer Banking: | Retail banking | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Consumer Banking: | Retail banking | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Commercial Banking:
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 616	$ 344
% of total class of receivables	0.69%	0.37%
Commercial Banking: | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Commercial Banking: | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	451	195
Commercial Banking: | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Commercial Banking: | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		17
Commercial Banking: | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	28	0
Commercial Banking: | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	137	132
Commercial Banking: | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 435	$ 129
% of total class of receivables	1.27%	0.35%
Commercial Banking: | Commercial and multifamily real estate | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Weighted-average interest rate reduction	0.79%	0.00%
Commercial Banking: | Commercial and multifamily real estate | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 316	$ 129
Payment delay duration (in months)	6 months	8 months
Commercial Banking: | Commercial and multifamily real estate | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Principal balance reduction	0	0
Commercial Banking: | Commercial and multifamily real estate | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		0
Commercial Banking: | Commercial and multifamily real estate | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	28	0
Commercial Banking: | Commercial and multifamily real estate | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	91	0
Commercial Banking: | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 181	$ 215
% of total class of receivables	0.33%	0.38%
Commercial Banking: | Commercial and industrial | Interest rate reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Weighted-average interest rate reduction	0.00%	0.00%
Commercial Banking: | Commercial and industrial | Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 135	$ 66
Payment delay duration (in months)	12 months	7 months
Commercial Banking: | Commercial and industrial | Principal balance reduction
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 0	$ 0
Principal balance reduction	15	3
Commercial Banking: | Commercial and industrial | Principal balance reduction and term extension
Financing Receivable, Past Due [Line Items]
Total loans modified		17
Commercial Banking: | Commercial and industrial | Interest Rate Reduction and Term Extension
Financing Receivable, Past Due [Line Items]
Total loans modified	0	0
Commercial Banking: | Commercial and industrial | Other
Financing Receivable, Past Due [Line Items]
Total loans modified	$ 46	$ 132