Reserves (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reserves For Losses (Textuals) [Abstract]
Participation interests in Card Member receivables purchased from affiliates	$ 5,400	$ 5,800	$ 3,400
Allowance for Card Member Receivables, Recoveries of Bad Debts	91	100	98
Allowance for Card Member Loans, Recoveries of Bad Debts	1	1	4
Participation Interest Card Member Receivables Sold to Affiliates	5,700	2,600	3,200
Amount of Card Member Loans Sold	$ 0	$ 0	$ 200