Reserves For Losses (Details Textuals) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	$ 5	$ 1
Card Member loans reserves for losses - other	11	11
Allowance for Card Member Receivables and Reserves, Recoveries of Bad Debts	93	101
Allowance for Card Member Loans, Recoveries of Bad Debts	100	88
Allowance for Card Member Receivables, Recoveries of Bad Debts - TDR	6	10
Allowance for Card Member Loans, Recoveries of Bad Debts - TDR	12	13
Unauthorized Transactions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	0
Card Member loans reserves for losses - other	0
Foreign Currency Translation Adjustments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	9	2
Card Member loans reserves for losses - other	7	2
Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Card Member receivables reserves for losses - other	(4)	(1)
Card Member loans reserves for losses - other	$ 4	2
CardMember loans transferred from HFS to held for investment		20
CardMember reserves associated with loans held for investments		$ 7