Reserves for Credit Losses - Changes in Receivables Reserve (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions for credit losses	$ 1,268	$ 1,198	$ 2,537	$ 2,253
Card Member Receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	151	223	174	229
Provisions for credit losses	226	230	422	452
Net write-offs	(205)	(243)	(422)	(473)
Other	(1)	0	(3)	2
Ending Balance	171	210	171	210
Recoveries	$ 78	$ 76	$ 154	$ 145