Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 3 — INCOME TAXES Our provision for income taxes for the quarters ended September 30, 2018 and 2017, was $173 million and $248 million, respectively, and the effective tax rates were 18.6% and 36.7%, respectively. Our provision for income taxes for the nine months ended September 30, 2018 and 2017, was $702 million and $902 million, respectively, and the effective tax rates were 20.5% and 34.1%, respectively. The reductions in the effective tax rates for 2018 periods were primarily related to the estimated impact of tax rate changes under the 2017 Tax Cuts and Jobs Act (the “Tax Act”). Our provision for income taxes for the quarter and nine months ended September 30, 2018 included tax benefits, of $132 million and $377 million, respectively, related to the reduction in our effective tax rate associated with the impact of the Tax Act. Our provision for income taxes also included tax benefits related to the settlement of employee equity awards of $23 million and $4 million for the quarters ended September 30, 2018 and 2017, respectively, and $119 million and $80 million for the nine months ended September 30, 2018 and 2017, respectively. We also recorded a reduction to the provision for income taxes of $28 million during the quarter ended September 30, 2018 for tax credits related to certain 2017 hurricane-related expenses. The Tax Act was enacted on December 22, 2017, and it significantly revised U.S. corporate income taxes, including lowering the federal statutory corporate tax rate from 35% to 21% beginning in 2018. Due to the complexity and uncertainty regarding numerous provisions of the Tax Act, we have not completed our accounting for its effects. However, we have made reasonable estimates and recorded provisional amounts in our financial statements as of September 30, 2018. As we complete our analysis of the Tax Act, we may make adjustments to the provisional amounts and record additional amounts for those federal, state, and foreign tax assets and liabilities for which we were unable to make reasonable estimates as of September 30, 2018. Any adjustments or additional amounts recorded may materially impact our provision for income taxes and effective tax rate in the periods in which they are made. Our liability for unrecognized tax benefits was $440 million, including accrued interest of $45 million, as of September 30, 2018 ($439 million and $44 million, respectively, as of December 31, 2017). Unrecognized tax benefits of $145 million ($145 million as of December 31, 2017) would affect the effective rate, if recognized. We are subject to examination by federal, state and foreign taxing authorities. Depending on the resolution of any federal, state and foreign tax disputes, the completion of examinations by federal, state or foreign taxing authorities, or the expiration of statutes of limitation for specific taxing jurisdictions, we believe it is reasonably possible that our liability for unrecognized tax benefits may significantly increase or decrease within the next 12 months. However, we are currently unable to estimate the range of any possible change.

NOTE 3 — INCOME TAXES

Our provision for income taxes for the quarters ended September 30, 2018 and 2017, was $173 million and $248 million, respectively, and the effective tax rates were 18.6% and 36.7%, respectively. Our provision for income taxes for the nine months ended September 30, 2018 and 2017, was $702 million and $902 million, respectively, and the effective tax rates were 20.5% and 34.1%, respectively. The reductions in the effective tax rates for 2018 periods were primarily related to the estimated impact of tax rate changes under the 2017 Tax Cuts and Jobs Act (the “Tax Act”). Our provision for income taxes for the quarter and nine months ended September 30, 2018 included tax benefits, of $132 million and $377 million, respectively, related to the reduction in our effective tax rate associated with the impact of the Tax Act. Our provision for income taxes also included tax benefits related to the settlement of employee equity awards of $23 million and $4 million for the quarters ended September 30, 2018 and 2017, respectively, and $119 million and $80 million for the nine months ended September 30, 2018 and 2017, respectively. We also recorded a reduction to the provision for income taxes of $28 million during the quarter ended September 30, 2018 for tax credits related to certain 2017 hurricane-related expenses.

The Tax Act was enacted on December 22, 2017, and it significantly revised U.S. corporate income taxes, including lowering the federal statutory corporate tax rate from 35% to 21% beginning in 2018. Due to the complexity and uncertainty regarding numerous provisions of the Tax Act, we have not completed our accounting for its effects. However, we have made reasonable estimates and recorded provisional amounts in our financial statements as of September 30, 2018. As we complete our analysis of the Tax Act, we may make adjustments to the provisional amounts and record additional amounts for those federal, state, and foreign tax assets and liabilities for which we were unable to make reasonable estimates as of September 30, 2018. Any adjustments or additional amounts recorded may materially impact our provision for income taxes and effective tax rate in the periods in which they are made.

Our liability for unrecognized tax benefits was $440 million, including accrued interest of $45 million, as of September 30, 2018 ($439 million and $44 million, respectively, as of December 31, 2017). Unrecognized tax benefits of $145 million ($145 million as of December 31, 2017) would affect the effective rate, if recognized.

We are subject to examination by federal, state and foreign taxing authorities. Depending on the resolution of any federal, state and foreign tax disputes, the completion of examinations by federal, state or foreign taxing authorities, or the expiration of statutes of limitation for specific taxing jurisdictions, we believe it is reasonably possible that our liability for unrecognized tax benefits may significantly increase or decrease within the next 12 months. However, we are currently unable to estimate the range of any possible change.