Service Fees and Other Revenue and Other Expenses - Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Service Fees and Other Revenue and Other Expenses [Abstract]
Data processing and equipment	$ 704	$ 651	$ 2,041	$ 1,874
Professional services	477	500	1,384	1,473
Net unrealized and realized losses on Amex Ventures investments	39	47	145	68
Other	385	376	1,143	1,008
Total Other expenses	$ 1,605	$ 1,574	$ 4,713	$ 4,423