Loans and Card Member Receivables - Credit Quality (Details)	Dec. 31, 2024	Dec. 31, 2023
Credit Quality Indicator for Loans and Receivables
90+ Days Past Billing as a % of total	0.40%	0.40%
Card Member loans | Consumer
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	1.40%	1.40%
Card Member loans | Small Business
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	1.50%	1.40%
Card Member loans | Net Write-Off Rate - Principal Only | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.20%	1.80%
Card Member loans | Net Write-Off Rate - Principal Only | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.30%	1.70%
Card Member loans | Net Write-Off Rate Principal Interest, and Fees | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.70%	2.20%
Card Member loans | Net Write-Off Rate Principal Interest, and Fees | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.60%	1.90%
Card Member receivables | Consumer
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	0.70%	0.90%
Card Member receivables | Small Business
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	1.20%	1.40%
Card Member receivables | Net Write-Off Rate - Principal Only | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.20%	1.50%
Card Member receivables | Net Write-Off Rate - Principal Only | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.90%	2.20%
Card Member receivables | Net Write-Off Rate Principal Interest, and Fees | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.30%	1.60%
Card Member receivables | Net Write-Off Rate Principal Interest, and Fees | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.00%	2.40%
Card Member receivables | Net Write-Off Rate Principal Interest, and Fees | Corporate
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	0.60%	0.60%