Loans and Card Member Receivables - Aging (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Card Member loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due	30 days
Financing receivables, gross	$ 151,832	$ 139,674
Threshold period past due for write-off	180 days
Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 117,719	107,646
Loans over 90 days past due and accruing interest	434	435
Non-accruals	471	464
Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	34,074	31,991
Loans over 90 days past due and accruing interest	130	132
Non-accruals	177	135
Card Member loans | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	39	37
Loans over 90 days past due and accruing interest	0	0
Non-accruals	$ 0	0
Card Member receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due	30 days
Financing receivables, gross	$ 62,031	59,411
Threshold period past due for write-off	180 days
Card Member receivables | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 26,605	25,431
Loans over 90 days past due and accruing interest	0	0
Non-accruals	0	0
Card Member receivables | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	19,558	18,619
Loans over 90 days past due and accruing interest	0	0
Non-accruals	0	0
Card Member receivables | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	15,868	15,361
Loans over 90 days past due and accruing interest	0	0
Non-accruals	0	0
Current | Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	116,148	106,155
Current | Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	33,528	31,510
Current | Card Member receivables | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	26,404	25,255
Current | Card Member receivables | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	19,342	18,400
30-59 Days Past Due | Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	473	437
30-59 Days Past Due | Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	173	151
30-59 Days Past Due | Card Member receivables | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	56	58
30-59 Days Past Due | Card Member receivables | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	82	77
60-89 Days Past Due | Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	350	329
60-89 Days Past Due | Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	121	107
60-89 Days Past Due | Card Member receivables | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	42	39
60-89 Days Past Due | Card Member receivables | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	47	54
90+ Days Past Due | Card Member loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	748	725
90+ Days Past Due | Card Member loans | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	252	223
90+ Days Past Due | Card Member loans | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	0	0
90+ Days Past Due | Card Member receivables | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	103	79
90+ Days Past Due | Card Member receivables | Small Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	88	88
90+ Days Past Due | Card Member receivables | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 75	$ 65