Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We manage our affairs so that we are centrally managed and controlled in the United Kingdom (“U.K.”) and therefore have our tax residency in the U.K. The provision for income taxes consists of provisions for the U.K. and international income taxes. We operate in an international environment with operations in various locations outside the U.K. Accordingly, the consolidated income tax rate is a composite rate reflecting the earnings in the various locations and the applicable rates. The effective income tax rate for the nine months ended September 30, 2018 was 17.0%, compared to 47.2% for the nine months ended September 30, 2017. We continue to actively pursue initiatives to reduce our effective tax rate. The tax rate in any quarter can be affected positively or negatively by adjustments that are required to be reported in the specific quarter of resolution. The liability for uncertain tax positions was $52.8 million and $12.0 million at September 30, 2018 and December 31, 2017, respectively. The increase was primarily due to the establishment of uncertain tax positions with the Internal Revenue Service and other jurisdictions. We record penalties and interest related to unrecognized tax benefits in Provision for income taxes and Net interest expense, respectively, on the Condensed Consolidated Statements of Operations and Comprehensive Income, which is consistent with our past practices. U.S. tax reform On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. For 2018, the Company considered in its estimated annual effective tax rate additional provisions of the Act including changes to the deduction for executive compensation and interest expense, a tax on global intangible low-taxed income provisions (“GILTI”), the base erosion anti-abuse tax, and a deduction for foreign-derived intangible income. The Company has elected to treat tax on GILTI income as a period cost and has therefore included it in its annual estimated effective tax rate. Given the significance of the Act, Staff Accounting Bulletin No. 118 (“SAB 118”) was issued to address the application of GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. SAB 118 allows registrants to record provisional amounts during a one year “measurement period.” The measurement period is deemed to have ended earlier when the registrant has obtained, prepared, and analyzed the information necessary to finalize its accounting. During the measurement period, impacts of the law are expected to be recorded at the time a reasonable estimate for all or a portion of the effects can be made, and provisional amounts can be recognized and adjusted as information becomes available, prepared, or analyzed. The Company calculated its best estimate of the impact of the Act in its December 31, 2017 income tax provision in accordance with its understanding of the Act and guidance available as of the date of the filing of the Annual Report on Form 10-K and as a result recorded a provisional income tax expense of $2.2 million in the fourth quarter of 2017, the period in which the legislation was enacted. For the three months ended September 30, 2018, we recorded a $3.6 million decrease to the provisional income tax expense. The provisional amount related to the remeasurement of certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future was a decrease to income tax expense of $28.0 million. The remeasurement of deferred taxes requires further analysis regarding the state tax impacts of the remeasurement and other aspects of the Act that may impact our tax balances. The amount related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings was an increase to income tax expense of $26.6 million. The determination of the transition tax requires additional analysis regarding state tax impacts, which is expected to be completed in the fourth quarter of 2018. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax, or any additional outside basis difference inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations.

Income Taxes

We manage our affairs so that we are centrally managed and controlled in the United Kingdom (“U.K.”) and therefore have our tax residency in the U.K. The provision for income taxes consists of provisions for the U.K. and international income taxes. We operate in an international environment with operations in various locations outside the U.K. Accordingly, the consolidated income tax rate is a composite rate reflecting the earnings in the various locations and the applicable rates.

The effective income tax rate for the nine months ended September 30, 2018 was 17.0%, compared to 47.2% for the nine months ended September 30, 2017. We continue to actively pursue initiatives to reduce our effective tax rate. The tax rate in any quarter can be affected positively or negatively by adjustments that are required to be reported in the specific quarter of resolution. The liability for uncertain tax positions was $52.8 million and $12.0 million at September 30, 2018 and December 31, 2017, respectively. The increase was primarily due to the establishment of uncertain tax positions with the Internal Revenue Service and other jurisdictions. We record penalties and interest related to unrecognized tax benefits in Provision for income taxes and Net interest expense, respectively, on the Condensed Consolidated Statements of Operations and Comprehensive Income, which is consistent with our past practices.

U.S. tax reform

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. For 2018, the Company considered in its estimated annual effective tax rate additional provisions of the Act including changes to the deduction for executive compensation and interest expense, a tax on global intangible low-taxed income provisions (“GILTI”), the base erosion anti-abuse tax, and a deduction for foreign-derived intangible income. The Company has elected to treat tax on GILTI income as a period cost and has therefore included it in its annual estimated effective tax rate.

Given the significance of the Act, Staff Accounting Bulletin No. 118 (“SAB 118”) was issued to address the application of GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. SAB 118 allows registrants to record provisional amounts during a one year “measurement period.” The measurement period is deemed to have ended earlier when the registrant has obtained, prepared, and analyzed the information necessary to finalize its accounting. During the measurement period, impacts of the law are expected to be recorded at the time a reasonable estimate for all or a portion of the effects can be made, and provisional amounts can be recognized and adjusted as information becomes available, prepared, or analyzed.

The Company calculated its best estimate of the impact of the Act in its December 31, 2017 income tax provision in accordance with its understanding of the Act and guidance available as of the date of the filing of the Annual Report on Form 10-K and as a result recorded a provisional income tax expense of $2.2 million in the fourth quarter of 2017, the period in which the legislation was enacted. For the three months ended September 30, 2018, we recorded a $3.6 million decrease to the provisional income tax expense. The provisional amount related to the remeasurement of certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future was a decrease to income tax expense of $28.0 million. The remeasurement of deferred taxes requires further analysis regarding the state tax impacts of the remeasurement and other aspects of the Act that may impact our tax balances.

The amount related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings was an increase to income tax expense of $26.6 million. The determination of the transition tax requires additional analysis regarding state tax impacts, which is expected to be completed in the fourth quarter of 2018. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax, or any additional outside basis difference inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations.