Regulatory Matters and Capital Adequacy (Details) $ in Millions	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 required, Minimum capital ratio	0.045
Risk-based capital required, Well-capitalized ratios, Minimum capital ratios	0.060
Minimum capital ratios	0.080
Leverage capital required, Minimum capital ratios	0.040
Parent Company | American Express Company
Regulatory capital ratios
CET1 capital	$ 23,174	$ 20,030
Tier 1 capital	24,779	21,627
Total capital	$ 28,784	$ 24,926
CET1 capital ratio	0.105	0.103
Tier 1 capital ratio	0.113	0.111
Total capital ratio	0.131	0.128
Tier 1 leverage ratio	0.099	0.099
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 required, Minimum capital ratio	0.070
Risk-based capital required, Well-capitalized ratios, Well-capitalized ratios	0.060
Risk-based capital required, Well-capitalized ratios, Minimum capital ratios, including buffer	0.085
Well-capitalized ratios	0.100
Minimum capital ratios	0.105
Leverage capital required, Minimum capital ratios	0.040
Subsidiaries | American Express National Bank
Regulatory capital ratios
CET1 capital	$ 17,038	$ 14,820
Tier 1 capital	17,038	14,820
Total capital	$ 19,548	$ 17,273
CET1 capital ratio	0.116	0.113
Tier 1 capital ratio	0.116	0.113
Total capital ratio	0.133	0.132
Tier 1 leverage ratio	0.095	0.097
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 required, Well-capitalized ratios	0.065
Common Equity Tier 1 required, Minimum capital ratio	0.070
Risk-based capital required, Well-capitalized ratios, Well-capitalized ratios	0.080
Risk-based capital required, Well-capitalized ratios, Minimum capital ratios, including buffer	0.085
Well-capitalized ratios	0.100
Minimum capital ratios	0.105
Leverage capital required, Well-capitalized ratios	0.050
Leverage capital required, Minimum capital ratios	0.040