Loans and Accounts Receivable (Details 7) pure in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	3	3	6	6
Aggregated Outstanding Balance Upon Payment Default	$ 12	$ 12	$ 23	$ 24
Card Member Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	2	2	4	4
Aggregated Outstanding Balance Upon Payment Default	$ 9	$ 10	$ 18	$ 21
Card Member Receivables [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts (in thousands)	1	1	2	2
Aggregated Outstanding Balance Upon Payment Default	$ 3	$ 2	$ 5	$ 3