Debt - Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Outstanding balance	$ 49,715	$ 47,866
Unamortized Underwriting Fees	(96)
Long-term Debt
Debt Instrument [Line Items]
Outstanding balance	$ 49,715	$ 47,866
Year-End Stated Rate on Debt (as a percent)	4.51%	3.96%
Unamortized Underwriting Fees	$ (96)	$ (93)
Parent Company
Debt Instrument [Line Items]
Outstanding balance	35,312	33,952
Fixed Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 14,582	$ 20,930
Year-End Stated Rate on Debt (as a percent)	3.66%	3.48%
Year-End Interest Rate with Swaps (as a percent)	3.80%	4.14%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | American Express Credit Corporation
Debt Instrument [Line Items]
Outstanding balance	$ 333	$ 330
Year-End Stated Rate on Debt (as a percent)	3.30%	3.30%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | Lending Trust
Debt Instrument [Line Items]
Outstanding balance	$ 13,934	$ 13,449
Year-End Stated Rate on Debt (as a percent)	4.23%	3.36%
Year-End Interest Rate with Swaps (as a percent)	4.32%	3.49%
Floating Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 3,000	$ 2,400
Year-End Stated Rate on Debt (as a percent)	5.49%	6.21%
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	$ 15,973	$ 8,769
Year-End Stated Rate on Debt (as a percent)	5.35%	5.38%
Year-End Interest Rate with Swaps (as a percent)	5.57%	5.91%
Fixed Rate Subordinated Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 0	$ 586
Year-End Stated Rate on Debt (as a percent)	0.00%	3.63%
Year-End Interest Rate with Swaps (as a percent)	0.00%	6.74%
Fixed-to-Floating Rate Subordinated Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 1,742	$ 1,257
Year-End Stated Rate on Debt (as a percent)	5.44%	5.24%
Year-End Interest Rate with Swaps (as a percent)	5.80%	5.92%
Floating Rate Borrowings | Subsidiaries | Long-term Debt | Other Subsidiaries
Debt Instrument [Line Items]
Outstanding balance	$ 247	$ 238
Year-End Stated Rate on Debt (as a percent)	0.76%	0.42%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%