Reserves for Credit Losses - Changes in Loan Reserve (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reserve for Losses [Roll Forward]
Provisions for credit losses	$ 1,233	$ 778	$ 3,486	$ 1,155
Card Member Loans
Reserve for Losses [Roll Forward]
Beginning Balance	4,390	2,997	3,747	3,305
Provisions for credit losses	982	596	2,691	757
Other	(12)	(15)	5	(22)
Ending Balance	4,721	3,319	4,721	3,319
Foreign currency translation adjustments	(13)	(16)	5	(22)
Card Member Loans | Principal
Reserve for Losses [Roll Forward]
Net write-offs	(525)	(203)	(1,412)	(560)
Recoveries	138	133	396	415
Card Member Loans | Interest and fees
Reserve for Losses [Roll Forward]
Net write-offs	$ (114)	$ (56)	$ (310)	$ (161)