Card Balances and Other Loans - Modifications (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Financing Receivable, Modifications [Line Items]
Maximum payment term extension			60 months
Unused credit available	$ 40	$ 38	$ 40	$ 38
Account Balances	1,005	946	1,998	1,837
Card Balances \| Interest Rate Reduction \| Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	$ 545	$ 520	$ 1,088	$ 1,005
% of Total Class of Financing Receivables	0.50%	0.50%	0.90%	0.90%
Weighted Average Interest Rate Reduction (% points)	18.10%	18.30%	18.10%	18.30%
Card Balances \| Interest Rate Reduction \| Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	$ 229	$ 205	$ 472	$ 409
% of Total Class of Financing Receivables	0.60%	0.60%	1.30%	1.20%
Weighted Average Interest Rate Reduction (% points)	18.10%	17.70%	18.10%	17.70%
Card Balances \| Interest Rate Reduction \| Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	$ 0	$ 0	$ 0	$ 0
% of Total Class of Financing Receivables	0.00%	0.00%	0.00%	0.00%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%	0.00%	0.00%
Card Balances \| Term Extension \| Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	$ 80	$ 69	$ 135	$ 130
% of Total Class of Financing Receivables	0.30%	0.30%	0.50%	0.50%
Weighted Average Payment Term Extensions (# of months)	30 months	31 months	31 months	31 months
Card Balances \| Term Extension \| Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	$ 106	$ 114	$ 220	$ 225
% of Total Class of Financing Receivables	0.50%	0.60%	1.10%	1.20%
Weighted Average Payment Term Extensions (# of months)	30 months	30 months	31 months	30 months
Card Balances \| Term Extension \| Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	$ 12	$ 12	$ 18	$ 16
% of Total Class of Financing Receivables	0.10%	0.10%	0.10%	0.10%
Weighted Average Payment Term Extensions (# of months)	10 months	10 months	10 months	10 months
Other Loans \| Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account Balances	$ 21	$ 17	$ 41	$ 32
% of Total Class of Financing Receivables	0.20%	0.20%	0.40%	0.30%
Weighted Average Interest Rate Reduction (% points)	3.80%	3.30%	3.80%	3.20%
Weighted Average Payment Term Extensions (# of months)	21 months	21 months	21 months	21 months
Other Loans \| Term Extension
Financing Receivable, Modifications [Line Items]
Account Balances	$ 12	$ 9	$ 23	$ 20
% of Total Class of Financing Receivables	0.10%	0.10%	0.20%	0.20%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%	0.00%	0.00%
Weighted Average Payment Term Extensions (# of months)	18 months	17 months	18 months	17 months

Financing Receivable, Modified, Maximum Term Increase From Modification For Customers On Fixed Payment Plans

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- Definition

Percentage of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amortized cost of financing receivable modified during period for debtor experiencing financial difficulty.

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- Definition

Percentage of decrease in weighted-average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

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Period of increase in weighted-average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable.

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