Income Taxes	6 Months Ended
Jun. 30, 2018
Income Taxes [Abstract]
Income Taxes	8. Income Taxes The results of operations of Credco are included in the consolidated U.S. federal income tax return of American Express. Under an agreement with American Express, provision for income taxes is recognized on a separate company basis. If benefits for net operating losses, future tax deductions and foreign tax credits cannot be recognized on a separate company basis, such benefits are then recognized based upon a share, derived by formula, of those deductions and credits that are recognizable on an American Express consolidated reporting basis. The effective tax rate was 5.4 percent and (9.6) percent for the three months ended June 30, 2018 and 2017, respectively, and (8.0) percent and 1.7 percent for the six months ended June 30, 2018 and 2017, respectively. The changes in tax rates for both periods primarily reflect a reduction in the U.S. statutory corporate income tax rate from 35 percent to 21 percent effective January 1, 2018, as a result of the Tax Act. The tax rate for the six months ended June 30, 2018 includes a $24 million discrete tax benefit that reduced the reported effective tax rate by 11.9 percent and is related to a revision to the provisional tax charge recorded in 2017 as a result of the Tax Act. The revision to the provisional tax charge results from additional analysis of the foreign withholding tax consequences of future cash dividends paid from non-U.S. subsidiaries. Credco is still analyzing the impacts of the Tax Act; therefore, the 2017 tax charge continues to be provisional. The tax rate in each of the periods reflects the geographic mix of expenses in the United States that generates a tax benefit at the U.S. statutory rate and foreign earnings taxed at lower rates, and the favorable impact of the tax benefit related to Credco’s ongoing funding activities outside the United States. Credco’s provision for income taxes for interim financial periods is not based on an estimated annual effective rate due to volatility in certain components of revenues and expenses that prevents Credco from projecting a reliable estimate of full year pretax income. A discrete calculation of the provision for income taxes is recorded for each interim period. American Express is under continuous examination by the Internal Revenue Service (IRS) and tax authorities in other countries and states in which American Express has significant business operations. The tax years under examination and open for examination vary by jurisdiction. American Express is currently under examination with the IRS for tax years 2008 through 2014. Credco believes it is reasonably possible that its unrecognized tax benefits could decrease by an immaterial amount within the next 12 months, principally as a result of potential resolutions of prior years’ tax items with various taxing authorities. The prior years’ tax items include unrecognized tax benefits relating to the attribution of taxable income to a particular jurisdiction or jurisdictions. The resolution of such items would not have a material impact on Credco’s effective tax rate.

8. Income Taxes

The results of operations of Credco are included in the consolidated U.S. federal income tax return of American Express. Under an agreement with American Express, provision for income taxes is recognized on a separate company basis. If benefits for net operating losses, future tax deductions and foreign tax credits cannot be recognized on a separate company basis, such benefits are then recognized based upon a share, derived by formula, of those deductions and credits that are recognizable on an American Express consolidated reporting basis.

The effective tax rate was 5.4 percent and (9.6) percent for the three months ended June 30, 2018 and 2017, respectively, and (8.0) percent and 1.7 percent for the six months ended June 30, 2018 and 2017, respectively. The changes in tax rates for both periods primarily reflect a reduction in the U.S. statutory corporate income tax rate from 35 percent to 21 percent effective January 1, 2018, as a result of the Tax Act. The tax rate for the six months ended June 30, 2018 includes a $24 million discrete tax benefit that reduced the reported effective tax rate by 11.9 percent and is related to a revision to the provisional tax charge recorded in 2017 as a result of the Tax Act. The revision to the provisional tax charge results from additional analysis of the foreign withholding tax consequences of future cash dividends paid from non-U.S. subsidiaries. Credco is still analyzing the impacts of the Tax Act; therefore, the 2017 tax charge continues to be provisional.

The tax rate in each of the periods reflects the geographic mix of expenses in the United States that generates a tax benefit at the U.S. statutory rate and foreign earnings taxed at lower rates, and the favorable impact of the tax benefit related to Credco’s ongoing funding activities outside the United States. Credco’s provision for income taxes for interim financial periods is not based on an estimated annual effective rate due to volatility in certain components of revenues and expenses that prevents Credco from projecting a reliable estimate of full year pretax income. A discrete calculation of the provision for income taxes is recorded for each interim period.

American Express is under continuous examination by the Internal Revenue Service (IRS) and tax authorities in other countries and states in which American Express has significant business operations. The tax years under examination and open for examination vary by jurisdiction. American Express is currently under examination with the IRS for tax years 2008 through 2014.

Credco believes it is reasonably possible that its unrecognized tax benefits could decrease by an immaterial amount within the next 12 months, principally as a result of potential resolutions of prior years’ tax items with various taxing authorities. The prior years’ tax items include unrecognized tax benefits relating to the attribution of taxable income to a particular jurisdiction or jurisdictions. The resolution of such items would not have a material impact on Credco’s effective tax rate.