Card Balances and Other Loans - Aging by Origination Year (Details) - Other Loans - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due	30 days
2026/2025	$ 5,091	$ 5,545
2025/2024	2,969	2,188
2024/2023	1,034	500
2023/2022	150	46
2022/2021	20	6
Prior	53	56
Revolving Loans	2,762	2,587
Total	12,079	10,928
2026/2025, gross write-offs	5	15
2025/2024, gross write-offs	61	77
2024/2023, gross write-offs	50	47
2023/2022, gross write-offs	16	13
2022/2021, gross write-offs	2	1
Prior, gross write-offs	0	0
Revolving Loans, gross write-offs	79	88
Total gross write-offs	213	242
Financing receivable, revolving, converted to term loan	5	0
Loans over 90 days past due and accruing interest	$ 9	7
Loans and receivables threshold period for write off	120 days
Non-accruals	$ 13	16
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
2026/2025	5,084	5,532
2025/2024	2,950	2,172
2024/2023	1,023	494
2023/2022	148	45
2022/2021	20	6
Prior	51	54
Revolving Loans	2,743	2,564
Total	12,019	10,867
30 to 59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2026/2025	3	6
2025/2024	8	7
2024/2023	4	2
2023/2022	1	0
2022/2021	0	0
Prior	0	1
Revolving Loans	8	8
Total	24	25
60 to 89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2026/2025	2	4
2025/2024	6	5
2024/2023	4	2
2023/2022	1	0
2022/2021	0	0
Prior	0	0
Revolving Loans	6	8
Total	19	19
90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
2026/2025	2	3
2025/2024	6	5
2024/2023	3	2
2023/2022	1	0
2022/2021	0	0
Prior	1	1
Revolving Loans	4	6
Total	$ 17	$ 17