Regulatory Matters and Capital Adequacy (Details) $ in Millions	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 required, Minimum capital ratio	0.045
Risk-based capital required, 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	$ 17,554	$ 18,693
Tier 1 capital	19,186	20,277
Total capital	$ 21,506	$ 22,385
CET1 capital ratio	0.105	0.135
Tier 1 capital ratio	0.115	0.147
Total capital ratio	0.129	0.162
Tier 1 leverage ratio	0.105	0.110
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 Required, Basel III Standards 2021	0.070
Risk-based capital required, Well-capitalized ratios	0.060
Tier 1 capital ratio, effective minimum	0.085
Well-capitalized ratios	0.100
Basel III Standards 2021	0.105
Leverage Capital Required, Basel III Standards 2020	0.040
Subsidiaries | American Express National Bank
Regulatory capital ratios
CET1 capital	$ 13,085	$ 14,617
Tier 1 capital	13,085	14,617
Total capital	$ 15,283	$ 16,578
CET1 capital ratio	0.118	0.162
Tier 1 capital ratio	0.118	0.162
Total capital ratio	0.137	0.183
Tier 1 leverage ratio	0.105	0.109
Regulatory Matters And Capital Adequacy
Common Equity Tier 1 required, Well-capitalized ratios	0.065
Common Equity Tier 1 Required, Basel III Standards 2021	0.070
Risk-based capital required, Well-capitalized ratios	0.080
Tier 1 capital ratio, effective minimum	0.085
Well-capitalized ratios	0.100
Basel III Standards 2021	0.105
Leverage capital required, Well-capitalized ratios	0.050
Leverage Capital Required, Basel III Standards 2020	0.040