Income Taxes	3 Months Ended
Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Tax Cuts and Jobs Act On December 22, 2017, the Tax Cuts and Jobs Act (the "2017 Tax Act") was signed into law. The 2017 Tax Act includes a broad range of tax reform provisions affecting businesses, including lower corporate tax rates, changes in business deductions, and international tax provisions. In response to the 2017 Tax Act, the U.S. Securities and Exchange Commission staff issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations where 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 2017 Tax Act. SAB 118 provides that the measurement period is complete when a company's accounting is complete and that measurement period shall not extend beyond one year from the enactment date. SAB 118 provides guidance for registrants under three scenarios: (i) measurement of certain income tax effects is complete, (ii) measurement of certain income tax effects can be reasonably estimated, and (iii) measurement of certain income tax effects cannot be reasonably estimated. The Company has analyzed the income tax effects of the 2017 Tax Act and determined that measurement of the income tax effects can be reasonably estimated, and, as such, provisional amounts have been recorded. For the three months ended December 31, 2017, the Company recognized discrete income tax benefits of $587.6 million in Income Tax Benefit on the Company's Consolidated Statement of Operations related to effects of the 2017 Tax Act, which are comprised of the following: (a) in accordance with Accounting Standards Codification No. 740, which requires deferred taxes to be remeasured in the year of an income tax rate change, the Company recorded a discrete deferred income tax benefit of $897.6 million in the three months ended December 31, 2017 as a result of applying a lower U.S. federal income tax rate to the Company's net deferred tax liabilities; and (b) the 2017 Tax Act also requires a one-time transition tax to be recognized on historical foreign earnings and profits. In the three months ended December 31, 2017, the Company recorded a discrete current income tax expense of $310.0 million on historical foreign earnings and profits through December 31, 2017. The measurement of income tax effects of the 2017 Tax Act cannot be completed until the end of the Company's current fiscal year due to the effective date of certain aspects of the 2017 Tax Act. Accordingly, the Company has recognized provisional amounts for the impact of the 2017 Tax Act within the accompanying interim unaudited consolidated financial statements as of and for the three months ended December 31, 2017 and expects to finalize the measurement of all amounts related to the 2017 Tax Act as of September 30, 2018. Other Information The Company files income tax returns in U.S. federal and state jurisdictions as well as various foreign jurisdictions. As of December 31, 2017, the Company had unrecognized tax benefits, defined as the aggregate tax effect of differences between tax return positions and the benefits recognized in the Company’s financial statements, of $249.0 million ($223.9 million, net of federal benefit). If recognized, $205.6 million of these tax benefits would reduce income tax expense and the effective tax rate. Included in this amount is $15.4 million of interest and penalties, which the Company records in income tax expense. In the three months ended December 31, 2017, unrecognized tax benefits decreased by $89.4 million primarily due to the impact of the 2017 Tax Act. Over the next 12 months, it is reasonably possible that state tax audit resolutions and the expiration of statutes of limitations could result in a reduction of unrecognized tax benefits by approximately $5.3 million. The Company's effective tax rates were (140.1)% and 31.9% in the three months ended December 31, 2017 and 2016, respectively. The effective tax rate in the three months ended December 31, 2017 was primarily impacted by the effect of the 2017 Tax Act. The effective tax rate in the three months ended December 31, 2016 was favorably impacted by growth of the Company's international businesses in Switzerland and Ireland, which have significantly lower income tax rates, and the benefit from stock option exercises and restricted stock vesting.

Income Taxes

Tax Cuts and Jobs Act

On December 22, 2017, the Tax Cuts and Jobs Act (the "2017 Tax Act") was signed into law. The 2017 Tax Act includes a broad range of tax reform provisions affecting businesses, including lower corporate tax rates, changes in business deductions, and international tax provisions. In response to the 2017 Tax Act, the U.S. Securities and Exchange Commission staff issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations where 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 2017 Tax Act. SAB 118 provides that the measurement period is complete when a company's accounting is complete and that measurement period shall not extend beyond one year from the enactment date. SAB 118 provides guidance for registrants under three scenarios: (i) measurement of certain income tax effects is complete, (ii) measurement of certain income tax effects can be reasonably estimated, and (iii) measurement of certain income tax effects cannot be reasonably estimated. The Company has analyzed the income tax effects of the 2017 Tax Act and determined that measurement of the income tax effects can be reasonably estimated, and, as such, provisional amounts have been recorded. For the three months ended December 31, 2017, the Company recognized discrete income tax benefits of $587.6 million in Income Tax Benefit on the Company's Consolidated Statement of Operations related to effects of the 2017 Tax Act, which are comprised of the following:

(a) in accordance with Accounting Standards Codification No. 740, which requires deferred taxes to be remeasured in the year of an income tax rate change, the Company recorded a discrete deferred income tax benefit of $897.6 million in the three months ended December 31, 2017 as a result of applying a lower U.S. federal income tax rate to the Company's net deferred tax liabilities; and

(b) the 2017 Tax Act also requires a one-time transition tax to be recognized on historical foreign earnings and profits. In the three months ended December 31, 2017, the Company recorded a discrete current income tax expense of $310.0 million on historical foreign earnings and profits through December 31, 2017.

The measurement of income tax effects of the 2017 Tax Act cannot be completed until the end of the Company's current fiscal year due to the effective date of certain aspects of the 2017 Tax Act. Accordingly, the Company has recognized provisional amounts for the impact of the 2017 Tax Act within the accompanying interim unaudited consolidated financial statements as of and for the three months ended December 31, 2017 and expects to finalize the measurement of all amounts related to the 2017 Tax Act as of September 30, 2018.

Other Information

The Company files income tax returns in U.S. federal and state jurisdictions as well as various foreign jurisdictions. As of December 31, 2017, the Company had unrecognized tax benefits, defined as the aggregate tax effect of differences between tax return positions and the benefits recognized in the Company’s financial statements, of $249.0 million ($223.9 million, net of federal benefit). If recognized, $205.6 million of these tax benefits would reduce income tax expense and the effective tax rate. Included in this amount is $15.4 million of interest and penalties, which the Company records in income tax expense. In the three months ended December 31, 2017, unrecognized tax benefits decreased by $89.4 million primarily due to the impact of the 2017 Tax Act. Over the next 12 months, it is reasonably possible that state tax audit resolutions and the expiration of statutes of limitations could result in a reduction of unrecognized tax benefits by approximately $5.3 million.

The Company's effective tax rates were (140.1)% and 31.9% in the three months ended December 31, 2017 and 2016, respectively. The effective tax rate in the three months ended December 31, 2017 was primarily impacted by the effect of the 2017 Tax Act. The effective tax rate in the three months ended December 31, 2016 was favorably impacted by growth of the Company's international businesses in Switzerland and Ireland, which have significantly lower income tax rates, and the benefit from stock option exercises and restricted stock vesting.