Other Fees and Commissions and Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Non Interest Income [Line Items]
Delinquency fees	$ 257	$ 238	$ 763	$ 712
Foreign currency conversion fee revenue	252	233	732	691
Travel commissions and fees	108	104	337	315
Loyalty coalition-related fees	106	120	329	338
Service fees and other	102	103	304	309
Other Fees and Commissions
Non Interest Income [Line Items]
Total Other fees and commissions	$ 825	$ 798	$ 2,465	$ 2,365