Other Fees and Commissions and Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Non Interest Income [Line Items]
Delinquency fees	$ 196	$ 255	$ 456	$ 506
Foreign currency conversion fee revenue	57	250	250	480
Loyalty coalition-related fees	90	109	198	223
Travel commissions and fees	5	121	65	229
Service fees and other	101	102	200	202
Other fees and commissions [Member]
Non Interest Income [Line Items]
Total Other fees and commissions	$ 449	$ 837	$ 1,169	$ 1,640