Loans and Card Member Receivables - Impaired Loans and Receivables, Prior to Adoption (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Impaired loans and receivables
Loans over 90 days past due and accruing interest			$ 309
Non-accruals			191
Account classified as a TDR in program			1,733
Account classified as a TDR out of program			2,068
Total impaired loans and receivables			4,301
Reserve for Credit Losses - TDRs			$ 504
Accounts Receivable and Loans Textuals
Threshold period past due for write-off			180 days
Account classified as TDR, past due 90 days and still accruing			$ 48
Accounts classified as TDR, non-accrual			17
Out of Program TDR accounts that completed modification programs			1,922
Out of Program TDR accounts not in compliance with modification programs			146
Card Member loans
Accounts Receivable and Loans Textuals
Threshold period past due for write-off	180 days
Card Member loans | Consumer
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 435	$ 393	252
Non-accruals	464	344	155
Account classified as a TDR in program			781
Account classified as a TDR out of program			1,098
Total impaired loans and receivables			2,286
Reserve for Credit Losses - TDRs			335
Card Member loans | Small Business
Impaired loans and receivables
Loans over 90 days past due and accruing interest	132	109	54
Non-accruals	135	95	34
Account classified as a TDR in program			267
Account classified as a TDR out of program			380
Total impaired loans and receivables			735
Reserve for Credit Losses - TDRs			108
Card Member loans | Corporate
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0	0
Non-accruals	$ 0	0	0
Account classified as a TDR in program			0
Account classified as a TDR out of program			0
Total impaired loans and receivables			0
Reserve for Credit Losses - TDRs			0
Card Member receivables
Accounts Receivable and Loans Textuals
Threshold period past due for write-off	180 days
Card Member receivables | Consumer
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 0	0	0
Non-accruals	0	0	0
Account classified as a TDR in program			257
Account classified as a TDR out of program			179
Total impaired loans and receivables			436
Reserve for Credit Losses - TDRs			20
Card Member receivables | Small Business
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0	0
Non-accruals	0	0	0
Account classified as a TDR in program			403
Account classified as a TDR out of program			402
Total impaired loans and receivables			805
Reserve for Credit Losses - TDRs			40
Card Member receivables | Corporate
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0	0
Non-accruals	$ 0	$ 0	0
Account classified as a TDR in program			6
Account classified as a TDR out of program			7
Total impaired loans and receivables			13
Reserve for Credit Losses - TDRs			1
Other Loans
Impaired loans and receivables
Loans over 90 days past due and accruing interest			3
Non-accruals			2
Account classified as a TDR in program			19
Account classified as a TDR out of program			2
Total impaired loans and receivables			26
Reserve for Credit Losses - TDRs			$ 0