Loans and Accounts Receivable (Details 7) pure in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	3	3	8	8
Aggregated Outstanding Balance Upon Payment Default	$ 15	$ 11	$ 37	$ 34
Card Member Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	2	2	5	5
Aggregated Outstanding Balance Upon Payment Default	$ 13	$ 9	$ 30	$ 30
Card Member Receivables [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	1	1	3	3
Aggregated Outstanding Balance Upon Payment Default	$ 2	$ 2	$ 7	$ 4