Reserves For Losses (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Card Member Receivables, Recoveries of Bad Debts	$ 367	$ 366	$ 394
Allowance for Card Member Loans, Recoveries of Bad Debts	444	409	379
Allowance for Card Member Receivables, Recoveries of Bad Debts - TDR	0	2	(16)
Allowance for Card Member Loans, Recoveries of Bad Debts - TDR	(33)	(30)	(34)
Loans Transferred From Held For Sale To Held For Investment		265
Cardmember Reserves For Loans Held For Investments		67
Foreign Currency Translation Adjustments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivable reserves for losses - Other	(6)	12	(12)
Card Member loans reserves for losses - other	(11)	8	(10)
Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivable reserves for losses - Other	(20)	(17)	(5)
Card Member loans reserves for losses - other	$ 16	$ 15	$ 8