Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Charge-Offs (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 180
2023	666
2022	899
2021	636
2020	264
Prior	256
Total Term Loans	2,901
Revolving Loans	10,719
Revolving Loans Converted to Term	129
Total	13,749
Credit Card:
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	10,629
Revolving Loans Converted to Term	128
Total	10,757
Credit Card: \| Domestic Card
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	10,132
Revolving Loans Converted to Term	114
Total	10,246
Credit Card: \| International card businesses
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	497
Revolving Loans Converted to Term	14
Total	511
Consumer Banking:
Financing Receivable, Credit Quality Indicator [Line Items]
2024	180
2023	666
2022	837
2021	599
2020	238
Prior	158
Total Term Loans	2,678
Revolving Loans	79
Revolving Loans Converted to Term	1
Total	2,758
Consumer Banking: \| Auto
Financing Receivable, Credit Quality Indicator [Line Items]
2024	179
2023	666
2022	837
2021	599
2020	237
Prior	156
Total Term Loans	2,674
Revolving Loans	0
Revolving Loans Converted to Term	0
Total	2,674
Consumer Banking: \| Retail banking
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1
2023	0
2022	0
2021	0
2020	1
Prior	2
Total Term Loans	4
Revolving Loans	79
Revolving Loans Converted to Term	1
Total	84
Commercial Banking:
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	62
2021	37
2020	26
Prior	98
Total Term Loans	223
Revolving Loans	11
Revolving Loans Converted to Term	0
Total	234
Commercial Banking: \| Commercial and multifamily real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	4
2021	31
2020	9
Prior	82
Total Term Loans	126
Revolving Loans	0
Revolving Loans Converted to Term	0
Total	126
Commercial Banking: \| Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	58
2021	6
2020	17
Prior	16
Total Term Loans	97
Revolving Loans	11
Revolving Loans Converted to Term	0
Total	$ 108

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