Reserves For Losses (Details Textuals) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other		$ 5	$ (2)
Card Member loans reserves for losses - other		19	68
Allowance for Card Member Receivables and Reserves, Recoveries of Bad Debts		181	202
Allowance for Card Member Loans, Recoveries of Bad Debts		205	179
Allowance for Card Member Receivables, Recoveries of Bad Debts - TDR		7	16
Allowance for Card Member Loans, Recoveries of Bad Debts - TDR		21	17
Foreign Currency Translation Adjustments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other		14	(1)
Card Member loans reserves for losses - other		10	(2)
Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other		(9)	(1)
Card Member loans reserves for losses - other		$ 9	3
CardMember loans transferred from HFS to held for investment	$ 20		245
CardMember reserves associated with loans held for investments	$ 7		$ 60