Income Taxes	6 Months Ended
Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act was enacted into law. The Tax Cuts and Jobs Act changes several aspects of US federal tax law including: reducing the US corporate income tax rate from 35.0% to 21.0% beginning on January 1, 2018; a one-time tax on the deemed mandatory repatriation of the Company's unremitted foreign earnings which have not been subject to US tax; imposing a minimum US tax on foreign earnings; providing for the immediate expensing of certain qualified property; and changing the tax treatment of performance-based executive compensation and certain employee fringe benefits. The SEC issued Staff Accounting Bulletin 118 allowing for provisional amounts to be recorded during a measurement period not to exceed one year. The Company recorded during the year ended December 31, 2017 provisional amounts for the impact of revaluing deferred tax assets and liabilities, the deemed mandatory repatriation tax on the Company's unremitted foreign earnings and the state income tax effects from the change in federal tax law during the year ended December 31, 2017. The Company did not adjust any of the provisional amounts during the three or six months ended June 30, 2018. The Company continues to analyze the income tax effects of the Tax Cuts and Jobs Act, as well as monitor guidance from the Internal Revenue Service, US Treasury Department and state taxing authorities and will adjust the provisional amounts within the one-year measurement period. Income tax expense was $57 million for the three months ended June 30, 2018, compared to $54 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 24.7% for the three months ended June 30, 2018 and differed from the US federal statutory rate of 21.0% primarily due to state income taxes partially offset by excess tax benefits on equity-based compensation. The effective tax rate for the same period of the prior year was 27.9% and differed from the US federal statutory rate of 35.0% primarily due to excess tax benefits on equity-based compensation. Income tax expense was $96 million for the six months ended June 30, 2018, compared to $71 million for the same period of the prior year. The effective income tax rate was 24.1% for the six months ended June 30, 2018 and differed from the US federal statutory rate of 21.0% primarily due to state income taxes partially offset by excess tax benefits on equity-based compensation. The effective tax rate for the same period of the prior year was 26.2% and differed from the US federal statutory rate primarily due to excess tax benefits on equity-based compensation.

Income Taxes

On December 22, 2017, the Tax Cuts and Jobs Act was enacted into law. The Tax Cuts and Jobs Act changes several aspects of US federal tax law including: reducing the US corporate income tax rate from 35.0% to 21.0% beginning on January 1, 2018; a one-time tax on the deemed mandatory repatriation of the Company's unremitted foreign earnings which have not been subject to US tax; imposing a minimum US tax on foreign earnings; providing for the immediate expensing of certain qualified property; and changing the tax treatment of performance-based executive compensation and certain employee fringe benefits.

The SEC issued Staff Accounting Bulletin 118 allowing for provisional amounts to be recorded during a measurement period not to exceed one year. The Company recorded during the year ended December 31, 2017 provisional amounts for the impact of revaluing deferred tax assets and liabilities, the deemed mandatory repatriation tax on the Company's unremitted foreign earnings and the state income tax effects from the change in federal tax law during the year ended December 31, 2017. The Company did not adjust any of the provisional amounts during the three or six months ended June 30, 2018. The Company continues to analyze the income tax effects of the Tax Cuts and Jobs Act, as well as monitor guidance from the Internal Revenue Service, US Treasury Department and state taxing authorities and will adjust the provisional amounts within the one-year measurement period.

Income tax expense was $57 million for the three months ended June 30, 2018, compared to $54 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 24.7% for the three months ended June 30, 2018 and differed from the US federal statutory rate of 21.0% primarily due to state income taxes partially offset by excess tax benefits on equity-based compensation. The effective tax rate for the same period of the prior year was 27.9% and differed from the US federal statutory rate of 35.0% primarily due to excess tax benefits on equity-based compensation.

Income tax expense was $96 million for the six months ended June 30, 2018, compared to $71 million for the same period of the prior year. The effective income tax rate was 24.1% for the six months ended June 30, 2018 and differed from the US federal statutory rate of 21.0% primarily due to state income taxes partially offset by excess tax benefits on equity-based compensation. The effective tax rate for the same period of the prior year was 26.2% and differed from the US federal statutory rate primarily due to excess tax benefits on equity-based compensation.