Non-Interest Revenue and Expense Detail (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Details Of Certain Statements Of Income Lines Details [Abstract]
Foreign currency conversion fee revenue	$ 888	$ 762	$ 788
Delinquency fees	851	809	852
Loyalty Partner-related fees	453	410	379
Travel Commissions And Fees	354	338	349
Service fees	309	291	361
Other	167	143	137
Total Other commissions and fees	$ 3,022	$ 2,753	$ 2,866