Regulatory Matters and Capital Adequacy (Details) $ in Millions	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
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
Supplementary leverage ratio, Well-capitalized, minimum	0.03
Parent Company \| American Express Company
Regulatory capital ratios
CET1 capital	$ 24,860	$ 23,174
Tier 1 capital	26,405	24,779
Total capital	$ 31,127	$ 28,784
CET1 capital ratio	0.105	0.105
Tier 1 capital ratio	0.112	0.113
Total capital ratio	0.132	0.131
Tier 1 leverage ratio	0.098	0.099
Supplementary Leverage Ratio	0.083
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
Supplementary leverage ratio, Well-capitalized, minimum	0.030
Subsidiaries \| American Express National Bank
Regulatory capital ratios
CET1 capital	$ 18,748	$ 17,038
Tier 1 capital	18,748	17,038
Total capital	$ 21,289	$ 19,548
CET1 capital ratio	0.116	0.116
Tier 1 capital ratio	0.116	0.116
Total capital ratio	0.132	0.133
Tier 1 leverage ratio	0.096	0.095
Supplementary Leverage Ratio	0.080
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
Supplementary leverage ratio, Well-capitalized, minimum	0.030

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Tier One Risk Based Capital Required For Capital Adequacy With Buffer To Risk Weighted Assets

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Ratio of minimum Common Equity Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

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