Reserves For Losses (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Card Member Receivables, Recoveries of Bad Debts	$ 391	$ 401	$ 358
Allowance for Card Member Loans, Recoveries of Bad Debts	379	418	428
Allowance for Card Member Receivables, Recoveries of Bad Debts - TDR	16	60	15
Allowance for Card Member Loans, Recoveries of Bad Debts - TDR	34	41	(10)
Card Member loans reserves for losses - other	8	10	12
Unauthorized Transactions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other		(7)
Card Member loans reserves for losses - other		(6)
Foreign Currency Translation Adjustments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	(12)	(16)	(15)
Card Member loans reserves for losses - other	(10)	(20)	(17)
Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	(5)	$ (11)	$ (8)
Loans Transferred From Held For Sale To Held For Investment	265
Cardmember Reserves For Loans Held For Investments	$ 67