Reserves for Credit Losses - Changes in Loan Reserve (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions	$ 985	$ 1,287	$ 3,320	$ 3,842
Card Balances
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning reserves	5,866	5,960	6,089	5,850
Provisions	895	1,220	3,099	3,587
Net write-offs	(1,130)	(1,111)	(3,550)	(3,397)
Other	3	(1)	(5)	28
Ending reserves	5,634	6,068	5,634	6,068
Recoveries	$ 380	$ 339	$ 1,148	$ 948