Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2019
Disclosure Text Block [Abstract]
Basis of Presentation	1. Basis of Presentation The Company We are a globally integrated payments company that provides customers with access to products, insights and experiences that enrich lives and build business success. Our principal products and services are charge and credit card products and travel-related services offered to consumers and businesses around the world. Business travel-related services are offered through the non-consolidated joint venture, American Express Global Business Travel (the GBT JV). Our various products and services are sold globally to diverse customer groups, including consumers, small businesses, mid-sized companies and large corporations. These products and services are sold through various channels, including mobile and online applications, direct mail, in-house sales teams, third-party vendors and direct response advertising. The accompanying Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2018 (the 2018 Form 10-K). If not materially different, certain note disclosures included therein have been omitted from these Consolidated Financial Statements. The interim consolidated financial information in this report has not been audited. In the opinion of management, all adjustments, which consist of normal recurring adjustments necessary for a fair statement of the interim period consolidated financial information, have been made. Results of operations reported for interim periods are not necessarily indicative of results for the entire year. The preparation of Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosures of contingent assets and liabilities. These accounting estimates reflect the best judgment of management, but actual results could differ. Certain reclassifications of prior period amounts have been made to conform to the current period presentation. Recently Issued Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued new accounting guidance for the recognition of credit losses on financial instruments, effective January 1, 2020. The guidance introduces a new credit reserving model known as the Current Expected Credit Loss (CECL) model, which is based on expected losses, and differs significantly from the incurred loss approach used today. The CECL model requires measurement of expected credit losses not only based on historical experience and current conditions, but also by including reasonable and supportable forecasts incorporating forward-looking information. In addition, for available-for-sale debt securities, the new guidance replaces the other-than-temporary impairment model, and requires the recognition of an allowance for reductions in a security’s fair value attributable to declines in credit quality, instead of a direct write-down of the security, when a valuation decline is determined to be other-than-temporary. The guidance also requires a cumulative-effect adjustment to retained earnings as of the beginning of the reporting period of adoption. We continue to evaluate the impact the new guidance will have on our financial position, results of operations and regulatory risk-based capital. The CECL model will alter the assumptions used in estimating credit losses on Card Member loans and receivables, and we may have material changes to our credit reserves as the new guidance involves earlier recognition of expected losses for the life of the assets. However, the extent of the impact will depend on the characteristics of our loan portfolio, macroeconomic conditions and forecasted information at the date of adoption. We continue to drive our cross-functional implementation efforts and have substantially completed development of CECL models. Continuing through 2019, we are validating and analyzing model output during CECL parallel runs, and developing the business processes, policies and controls that satisfy the requirements of the new standard. Recently Adopted Accounting Standards In February 2016, the FASB issued new accounting guidance on leases. The accounting standard, effective January 1, 2019, requires virtually all leases to be recognized on the Consolidated Balance Sheets. Effective January 1, 2019, we adopted the standard using the modified retrospective method, under which we elected the package of practical expedients and transition provisions allowing us to bring our existing operating leases onto the Consolidated Balance Sheet without adjusting comparative periods. Under the guidance we have also elected not to separate lease and non-lease components in recognition of the lease-related assets and liabilities, as well as the related lease expense. We have operating leases for facilities and equipment, which are recorded as assets and liabilities for those leases with terms greater than 12 months. Lease-related assets, or right-of-use assets, are recognized at the lease commencement date at amounts equal to the respective lease liabilities, adjusted for prepaid lease payments, initial direct costs, and lease incentives received. Lease-related liabilities are recognized at the present value of the remaining contractual fixed lease payments, discounted using our incremental borrowing rate. Operating lease expense is recognized on a straight-line basis over the lease term, while variable lease payments are expensed as incurred. Upon adoption of the standard, we recorded approximately $700 million of right of use assets and lease-related liabilities, included in Other assets and Other liabilities, respectively. In conjunction with the adoption, we upgraded our lease administration software and updated our business processes and internal controls in support of the new guidance. In February 2018, as a result of the enactment of the Tax Cuts and Jobs Act (the Tax Act), the FASB issued new accounting guidance on the reclassification of certain tax effects from accumulated other comprehensive income (AOCI) to retained earnings. We adopted the new guidance effective January 1, 2019 and did not elect the optional reclassification.

1. Basis of Presentation

The Company

We are a globally integrated payments company that provides customers with access to products, insights and experiences that enrich lives and build business success. Our principal products and services are charge and credit card products and travel-related services offered to consumers and businesses around the world. Business travel-related services are offered through the non-consolidated joint venture, American Express Global Business Travel (the GBT JV). Our various products and services are sold globally to diverse customer groups, including consumers, small businesses, mid-sized companies and large corporations. These products and services are sold through various channels, including mobile and online applications, direct mail, in-house sales teams, third-party vendors and direct response advertising.

The accompanying Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2018 (the 2018 Form 10-K). If not materially different, certain note disclosures included therein have been omitted from these Consolidated Financial Statements.

The interim consolidated financial information in this report has not been audited. In the opinion of management, all adjustments, which consist of normal recurring adjustments necessary for a fair statement of the interim period consolidated financial information, have been made. Results of operations reported for interim periods are not necessarily indicative of results for the entire year.

The preparation of Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosures of contingent assets and liabilities. These accounting estimates reflect the best judgment of management, but actual results could differ.

Certain reclassifications of prior period amounts have been made to conform to the current period presentation.

Recently Issued Accounting Standards

In June 2016, the Financial Accounting Standards Board (FASB) issued new accounting guidance for the recognition of credit losses on financial instruments, effective January 1, 2020. The guidance introduces a new credit reserving model known as the Current Expected Credit Loss (CECL) model, which is based on expected losses, and differs significantly from the incurred loss approach used today. The CECL model requires measurement of expected credit losses not only based on historical experience and current conditions, but also by including reasonable and supportable forecasts incorporating forward-looking information. In addition, for available-for-sale debt securities, the new guidance replaces the other-than-temporary impairment model, and requires the recognition of an allowance for reductions in a security’s fair value attributable to declines in credit quality, instead of a direct write-down of the security, when a valuation decline is determined to be other-than-temporary. The guidance also requires a cumulative-effect adjustment to retained earnings as of the beginning of the reporting period of adoption. We continue to evaluate the impact the new guidance will have on our financial position, results of operations and regulatory risk-based capital. The CECL model will alter the assumptions used in estimating credit losses on Card Member loans and receivables, and we may have material changes to our credit reserves as the new guidance involves earlier recognition of expected losses for the life of the assets. However, the extent of the impact will depend on the characteristics of our loan portfolio, macroeconomic conditions and forecasted information at the date of adoption. We continue to drive our cross-functional implementation efforts and have substantially completed development of CECL models. Continuing through 2019, we are validating and analyzing model output during CECL parallel runs, and developing the business processes, policies and controls that satisfy the requirements of the new standard.

Recently Adopted Accounting Standards

In February 2016, the FASB issued new accounting guidance on leases. The accounting standard, effective January 1, 2019, requires virtually all leases to be recognized on the Consolidated Balance Sheets. Effective January 1, 2019, we adopted the standard using the modified retrospective method, under which we elected the package of practical expedients and transition provisions allowing us to bring our existing operating leases onto the Consolidated Balance Sheet without adjusting comparative periods. Under the guidance we have also elected not to separate lease and non-lease components in recognition of the lease-related assets and liabilities, as well as the related lease expense.

We have operating leases for facilities and equipment, which are recorded as assets and liabilities for those leases with terms greater than 12 months. Lease-related assets, or right-of-use assets, are recognized at the lease commencement date at amounts equal to the respective lease liabilities, adjusted for prepaid lease payments, initial direct costs, and lease incentives received. Lease-related liabilities are recognized at the present value of the remaining contractual fixed lease payments, discounted using our incremental borrowing rate. Operating lease expense is recognized on a straight-line basis over the lease term, while variable lease payments are expensed as incurred.

Upon adoption of the standard, we recorded approximately $700 million of right of use assets and lease-related liabilities, included in Other assets and Other liabilities, respectively. In conjunction with the adoption, we upgraded our lease administration software and updated our business processes and internal controls in support of the new guidance.

In February 2018, as a result of the enactment of the Tax Cuts and Jobs Act (the Tax Act), the FASB issued new accounting guidance on the reclassification of certain tax effects from accumulated other comprehensive income (AOCI) to retained earnings. We adopted the new guidance effective January 1, 2019 and did not elect the optional reclassification.