Loans and Card Member Receivables - Aging by Origination Year (Details) - Other loans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due	30 days
2025/2024	$ 5,545	$ 4,964
2024/2023	2,188	1,591
2023/2022	500	362
2022/2021	46	10
2021/2020	6	14
Prior	56	58
Revolving Loans	2,587	2,233
Total	10,928	9,232
2025/2024, gross write-offs	15	13
2024/2023, gross write-offs	77	59
2023/2022, gross write-offs	47	42
2022/2021, gross write-offs	13	6
2021/2020, gross write-offs	1	0
Prior, gross write-offs	0	0
Revolving Loans, gross write-offs	88	87
Total gross write-offs	242	207
Loans over 90 days past due and accruing interest	$ 7	6
Threshold period past due for write-off	120 days
Non-accruals	$ 16	19
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025/2024	5,532	4,950
2024/2023	2,172	1,578
2023/2022	494	356
2022/2021	45	10
2021/2020	6	14
Prior	54	57
Revolving Loans	2,564	2,209
Total	10,867	9,174
30-59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025/2024	6	5
2024/2023	7	5
2023/2022	2	2
2022/2021	0	0
2021/2020	0	0
Prior	1	0
Revolving Loans	8	10
Total	25	22
60-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025/2024	4	5
2024/2023	5	4
2023/2022	2	2
2022/2021	0	0
2021/2020	0	0
Prior	0	0
Revolving Loans	8	7
Total	19	18
90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2025/2024	3	4
2024/2023	5	4
2023/2022	2	2
2022/2021	0	0
2021/2020	0	0
Prior	1	1
Revolving Loans	6	7
Total	$ 17	$ 18