Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For interim income tax reporting we estimate our annual effective tax rate and apply it to our year-to-date ordinary income. Tax jurisdictions with a projected or year-to-date loss for which a tax benefit cannot be realized are excluded from the annualized effective tax rate. The tax effects of unusual or infrequently occurring items, including changes in judgment about valuation allowances and effects of changes in tax laws or rates, are reported in the interim period in which they occur. During the three and nine months ended September 30, 2018, income tax expense of $57 million and $225 million primarily resulted from tax expense attributable to entities included in our effective tax rate calculation. During the three and nine months ended September 30, 2017, income tax expense of $124 million and $260 million primarily resulted from tax expense attributable to entities included in our effective tax rate calculation. We are included in GM’s consolidated U.S. federal income tax return and for certain states’ income tax returns. Net operating losses and certain tax credits generated by us have been utilized by GM; however, income tax expense and deferred tax balances are presented in these financial statements as if we filed our own tax returns in each jurisdiction. On December 22, 2017, the Tax Act was signed into law. The Tax Act changed many aspects of U.S. corporate income taxation, including the reduction of the corporate income tax rate from 35% to 21%, implementation of a territorial tax system and imposition of a tax on deemed repatriated earnings of foreign subsidiaries. At December 31, 2017, we had not completed our accounting for the tax effects of enactment of the Tax Act; however, we made a reasonable estimate of the effects on our existing deferred tax balances and the one-time transition tax. In the three months ended September 30, 2018, we filed our 2017 U.S. federal income tax return and updated our 2017 estimated tax benefit from $240 million to $286 million, primarily related to the remeasurement of transition tax as a result of proposed regulations issued in August 2018 and associated impacts to our deferred tax asset carryforwards. We will continue to assess our provision for income taxes as future guidance is issued, but do not currently anticipate significant revisions will be necessary. Any such revisions will be treated in accordance with the measurement period guidance outlined in Staff Accounting Bulletin No. 118.

Income Taxes

For interim income tax reporting we estimate our annual effective tax rate and apply it to our year-to-date ordinary income. Tax jurisdictions with a projected or year-to-date loss for which a tax benefit cannot be realized are excluded from the annualized effective tax rate. The tax effects of unusual or infrequently occurring items, including changes in judgment about valuation allowances and effects of changes in tax laws or rates, are reported in the interim period in which they occur.

During the three and nine months ended September 30, 2018, income tax expense of $57 million and $225 million primarily resulted from tax expense attributable to entities included in our effective tax rate calculation. During the three and nine months ended September 30, 2017, income tax expense of $124 million and $260 million primarily resulted from tax expense attributable to entities included in our effective tax rate calculation.

We are included in GM’s consolidated U.S. federal income tax return and for certain states’ income tax returns. Net operating losses and certain tax credits generated by us have been utilized by GM; however, income tax expense and deferred tax balances are presented in these financial statements as if we filed our own tax returns in each jurisdiction.

On December 22, 2017, the Tax Act was signed into law. The Tax Act changed many aspects of U.S. corporate income taxation, including the reduction of the corporate income tax rate from 35% to 21%, implementation of a territorial tax system and imposition of a tax on deemed repatriated earnings of foreign subsidiaries. At December 31, 2017, we had not completed our accounting for the tax effects of enactment of the Tax Act; however, we made a reasonable estimate of the effects on our existing deferred tax balances and the one-time transition tax. In the three months ended September 30, 2018, we filed our 2017 U.S. federal income tax return and updated our 2017 estimated tax benefit from $240 million to $286 million, primarily related to the remeasurement of transition tax as a result of proposed regulations issued in August 2018 and associated impacts to our deferred tax asset carryforwards. We will continue to assess our provision for income taxes as future guidance is issued, but do not currently anticipate significant revisions will be necessary. Any such revisions will be treated in accordance with the measurement period guidance outlined in Staff Accounting Bulletin No. 118.