Loans and Card Member Receivables - Credit Quality (Details)	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
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	2.10%	2.20%
Card Member Loans | Net Write-Off Rate - Principal Only | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.50%	2.20%
Card Member Loans | Net Write-Off Rate Principal Interest, and Fees | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.60%	2.80%
Card Member Loans | Net Write-Off Rate Principal Interest, and Fees | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.90%	2.60%
Card Member Receivables | Consumer
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	1.00%	0.80%
Card Member Receivables | Small Business
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	1.10%	1.20%
Card Member Receivables | Net Write-Off Rate - Principal Only | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.00%	1.30%
Card Member Receivables | Net Write-Off Rate - Principal Only | Small Business
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.80%	2.00%
Card Member Receivables | Net Write-Off Rate Principal Interest, and Fees | Consumer
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	1.10%	1.40%
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%	2.10%
Card Member Receivables | Net Write-Off Rate Principal Interest, and Fees | Corporate
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	0.50%	0.60%
Other Loans
Credit Quality Indicator for Loans and Receivables
30+ Days Past Due as a % of Total	0.60%	0.70%
Other Loans | Net Write-Off Rate - Principal Only
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.00%	2.20%
Other Loans | Net Write-Off Rate Principal Interest, and Fees
Credit Quality Indicator for Loans and Receivables
Net Write-Off Rate	2.10%	2.30%