Other Fees and Commissions and Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fees charged to Card Members:
Delinquency fees	$ 166	$ 159	$ 460	$ 615
Foreign currency conversion fee revenue	142	86	347	336
Other customer fees:
Loyalty coalition-related fees	123	112	368	309
Travel commissions and fees	74	19	164	84
Service fees and other	127	102	373	303
Other fees and commissions
Other customer fees:
Total Other fees and commissions	$ 632	$ 478	$ 1,712	$ 1,647