Reserves For Losses (Details Textuals) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables net write-offs	$ (435)	$ (373)
Allowance for Card Member Receivables, Recoveries of Bad Debts	174	181
Allowance for Card Member Loans, Recoveries of Bad Debts	217	205
Allowance for Card Member Receivables, Recoveries of Bad Debts - TDR	2	(7)
Allowance for Card Member Loans, Recoveries of Bad Debts - TDR	(14)	(21)
Other	2	19
Other	(15)	5
Foreign Currency Translation Adjustments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other	(5)	10
Other	(1)	14
Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other	7	9
Other	$ (14)	$ (9)