Reserves for Credit Losses - Change in Receivables 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 Receivables
Reserve for Losses [Roll Forward]
Beginning Balance	210	119	229	64
Provisions for credit losses	206	165	658	383
Net write-offs	(241)	(122)	(714)	(284)
Other	(1)	(3)	1	(4)
Ending Balance	174	159	174	159
Recoveries	$ 73	$ 60	$ 218	$ 195