Card Member Receivables and Card Member Loans 3 (Details)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Global Consumer Services Group [Member] | Card Member Receivables [Member] | Net Write-Off Rate [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	1.24%	0.99%
Global Consumer Services Group [Member] | Card Member Receivables [Member] | 30+ Days Past Due as a % of Total [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.62%	0.88%
Global Consumer Services Group [Member] | Card Member Loans [Member] | Net Write-Off Rate [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.93%	1.41%
Global Consumer Services Group [Member] | Card Member Loans [Member] | 30+ Days Past Due as a % of Total [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.68%	0.80%
Global Small Business Services [Member] | Card Member Receivables [Member] | Net Write-Off Rate [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	1.51%	1.01%
Global Small Business Services [Member] | Card Member Receivables [Member] | 30+ Days Past Due as a % of Total [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.86%	1.10%
Global Corporate Payments [Member] | Card Member Receivables [Member] | Net Loss Ratio as a % of Charge Volume [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.07%	0.07%
Global Corporate Payments [Member] | Card Member Receivables [Member] | 90+ days past billing as a percentage of receivables [Member]
Credit Quality Indicator for Receivables and Loans
Credit Quality Indicators	0.78%	0.89%