Loans and Card Member Receivables - Modifications (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Modifications [Line Items]
Maximum payment term extension	60 months
Unused credit available	$ 19	$ 28
Account Balances	1,021	1,115
Card Member Loans \| Interest Rate Reduction \| Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	$ 545	$ 586
% of Total Class of Financing Receivables	0.50%	0.60%
Weighted Average Interest Rate Reduction (% points)	18.40%	18.00%
Card Member Loans \| Interest Rate Reduction \| Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	$ 229	$ 206
% of Total Class of Financing Receivables	0.70%	0.70%
Weighted Average Interest Rate Reduction (% points)	17.70%	17.40%
Card Member Loans \| Interest Rate Reduction \| Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	$ 0	$ 0
% of Total Class of Financing Receivables	0.00%	0.00%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%
Card Member Receivables \| Term Extension \| Consumer
Financing Receivable, Modifications [Line Items]
Account Balances	$ 76	$ 114
% of Total Class of Financing Receivables	0.30%	0.50%
Weighted Average Payment Term Extensions (# of months)	31 months	29 months
Card Member Receivables \| Term Extension \| Small Business
Financing Receivable, Modifications [Line Items]
Account Balances	$ 137	$ 174
% of Total Class of Financing Receivables	0.70%	0.90%
Weighted Average Payment Term Extensions (# of months)	29 months	29 months
Card Member Receivables \| Term Extension \| Corporate
Financing Receivable, Modifications [Line Items]
Account Balances	$ 5	$ 6
% of Total Class of Financing Receivables	0.03%	0.04%
Weighted Average Payment Term Extensions (# of months)	11 months	9 months
Other Loans \| Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Account Balances	$ 17	$ 18
% of Total Class of Financing Receivables	0.20%	0.20%
Weighted Average Interest Rate Reduction (% points)	3.10%	2.30%
Weighted Average Payment Term Extensions (# of months)	21 months	19 months
Other Loans \| Term Extension
Financing Receivable, Modifications [Line Items]
Account Balances	$ 12	$ 11
% of Total Class of Financing Receivables	0.10%	0.10%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%
Weighted Average Payment Term Extensions (# of months)	17 months	19 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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- Definition

Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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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