Other Fees and Commissions and Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Non Interest Income [Line Items]
Delinquency fees	$ 159	$ 257	$ 615	$ 763
Foreign currency conversion fee revenue	86	252	336	732
Loyalty coalition-related fees	112	106	309	329
Travel commissions and fees	19	108	84	337
Service fees and other	102	102	303	304
Other fees and commissions [Member]
Non Interest Income [Line Items]
Total Other fees and commissions	$ 478	$ 825	$ 1,647	$ 2,465