Debt - Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Outstanding balance	$ 47,866	$ 42,573
Unamortized Underwriting Fees	(93)
Long-term Debt
Debt Instrument [Line Items]
Outstanding balance	$ 47,866	$ 42,573
Year-End Stated Rate on Debt (as a percent)	3.96%	3.42%
Unamortized Underwriting Fees	$ (93)	$ (84)
Parent Company
Debt Instrument [Line Items]
Outstanding balance	33,952	29,432
Fixed Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 20,930	$ 23,813
Year-End Stated Rate on Debt (as a percent)	3.48%	3.34%
Year-End Interest Rate with Swaps (as a percent)	4.14%	4.00%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | American Express Credit Corporation
Debt Instrument [Line Items]
Outstanding balance	$ 330	$ 328
Year-End Stated Rate on Debt (as a percent)	3.30%	3.30%
Year-End Interest Rate with Swaps (as a percent)		0.00%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | Lending Trust
Debt Instrument [Line Items]
Outstanding balance	$ 13,449	$ 10,499
Year-End Stated Rate on Debt (as a percent)	3.36%	2.81%
Year-End Interest Rate with Swaps (as a percent)	3.49%	0.00%
Floating Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 2,400	$ 3,000
Year-End Stated Rate on Debt (as a percent)	6.21%	4.78%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%
Floating Rate Senior Notes | Subsidiaries | Long-term Debt | Lending Trust
Debt Instrument [Line Items]
Outstanding balance	$ 0	$ 2,125
Year-End Stated Rate on Debt (as a percent)	0.00%	4.67%
Year-End Interest Rate with Swaps (as a percent)		0.00%
Fixed-to-Floating Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 8,769	$ 1,250
Year-End Stated Rate on Debt (as a percent)	5.38%	4.42%
Year-End Interest Rate with Swaps (as a percent)	5.91%	0.00%
Fixed Rate Subordinated Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 586	$ 574
Year-End Stated Rate on Debt (as a percent)	3.63%	3.63%
Year-End Interest Rate with Swaps (as a percent)	6.74%	5.46%
Fixed-to-Floating Rate Subordinated Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 1,257	$ 750
Year-End Stated Rate on Debt (as a percent)	5.24%	4.99%
Year-End Interest Rate with Swaps (as a percent)	5.92%	0.00%
Floating Rate Subordinated Notes | Subsidiaries | Long-term Debt | Lending Trust
Debt Instrument [Line Items]
Outstanding balance	$ 0	$ 61
Year-End Stated Rate on Debt (as a percent)	0.00%	4.89%
Year-End Interest Rate with Swaps (as a percent)		0.00%
Fixed Rate Instruments | Subsidiaries | Financed Leases | Long-term Debt | Other Subsidiaries
Debt Instrument [Line Items]
Outstanding balance	$ 0	$ 3
Year-End Stated Rate on Debt (as a percent)	0.00%	5.76%
Year-End Interest Rate with Swaps (as a percent)		0.00%
Floating Rate Borrowings | Subsidiaries | Long-term Debt | Other Subsidiaries
Debt Instrument [Line Items]
Outstanding balance	$ 238	$ 254
Year-End Stated Rate on Debt (as a percent)	0.42%	0.41%
Year-End Interest Rate with Swaps (as a percent)		0.00%