Reserves for Credit Losses - Changes in Receivables Reserve (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions for credit losses	$ 1,269	$ 1,055
Card Member Receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	174	229
Provisions for credit losses	196	222
Net write-offs	(217)	(230)
Other	(2)	2
Ending Balance	151	223
Recoveries	$ 76	$ 69