Income Taxes	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rates were 17.6% and 29.2% for the three months ended March 31, 2018 and 2017, respectively. The effective income tax rate for the three months ended March 31, 2018 was lower than the U.S. federal income tax rate of 21% due to the impact of foreign operations and $1.6 million of excess tax benefits from share-based compensation, partially offset by state income taxes. The effective income tax rate for the three months ended March 31, 2017 was lower than the U.S. federal income tax rate of 35% due to the impact of foreign operations and $1.2 million of excess tax benefits from share-based compensation, partially offset by state income taxes. The Tax Cuts and Jobs Act (the "Act") was enacted on December 22, 2017. The Act reduces the U.S. federal corporate income tax rate from 35.0% to 21.0%, requires companies to pay a one-time transition tax on earnings of foreign subsidiaries that were previously tax deferred, and creates new taxes on certain foreign-sourced earnings. The Company applied the guidance in Staff Accounting Bulletin 118 when accounting for the enactment-date effects of the Act. As of March 31, 2018, the Company made a reasonable estimate of the tax effects of the Act and will continue to refine its calculations as additional analysis is completed. Estimates may also be affected as additional clarification and understanding of the tax law is provided. These changes could be material to income tax expense. The Act subjects a U.S. shareholder to a minimum tax on “global intangible low-taxed income” ("GILTI") earned by certain foreign subsidiaries. The FASB Staff Q&A, Topic 740 No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity can make an accounting policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI resulting from those items in the year the tax is incurred. The Company has elected to recognize the resulting tax on GILTI as a period expense in the period the tax is incurred and expects to incur tax for the year ended December 31, 2018.

Income Taxes

The effective income tax rates were 17.6% and 29.2% for the three months ended March 31, 2018 and 2017, respectively. The effective income tax rate for the three months ended March 31, 2018 was lower than the U.S. federal income tax rate of 21% due to the impact of foreign operations and $1.6 million of excess tax benefits from share-based compensation, partially offset by state income taxes. The effective income tax rate for the three months ended March 31, 2017 was lower than the U.S. federal income tax rate of 35% due to the impact of foreign operations and $1.2 million of excess tax benefits from share-based compensation, partially offset by state income taxes.

The Tax Cuts and Jobs Act (the "Act") was enacted on December 22, 2017. The Act reduces the U.S. federal corporate income tax rate from 35.0% to 21.0%, requires companies to pay a one-time transition tax on earnings of foreign subsidiaries that were previously tax deferred, and creates new taxes on certain foreign-sourced earnings. The Company applied the guidance in Staff Accounting Bulletin 118 when accounting for the enactment-date effects of the Act. As of March 31, 2018, the Company made a reasonable estimate of the tax effects of the Act and will continue to refine its calculations as additional analysis is completed. Estimates may also be affected as additional clarification and understanding of the tax law is provided. These changes could be material to income tax expense.

The Act subjects a U.S. shareholder to a minimum tax on “global intangible low-taxed income” ("GILTI") earned by certain foreign subsidiaries. The FASB Staff Q&A, Topic 740 No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity can make an accounting policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI resulting from those items in the year the tax is incurred. The Company has elected to recognize the resulting tax on GILTI as a period expense in the period the tax is incurred and expects to incur tax for the year ended December 31, 2018.