Income Taxes	6 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is incorporated in Switzerland but operates in various countries with differing tax laws and rates. Further, a portion of the Company’s income before taxes and the provision for (benefit from) income taxes are generated outside of Switzerland. The Company has not adjusted the net provisional charge from remeasuring deferred tax assets related to the Tax Cuts and Jobs Act (the "Tax Act") in the United States in fiscal year 2018. The Company continues to refine the estimate based on ongoing analysis and available information and interpretations through the third quarter of fiscal year 2019. The income tax provision for the three months ended September 30, 2018 was $6.2 million based on an effective income tax rate of 8.8% of pre-tax income, compared to an income tax provision of $4.1 million based on an effective income tax rate of 6.8% of pre-tax income for the three months ended September 30, 2017. The income tax provision for the six months ended September 30, 2018 was $1.0 million based on an effective income tax rate of 1.0% of pre-tax income, compared to an income tax benefit of $1.3 million based on an effective income tax rate of (1.5)% of pre-tax income for the six months ended September 30, 2017. The changes in the effective income tax rate for the three and six months ended September 30, 2018, compared to the three and six months ended September 30, 2017, were primarily due to the mix of income and losses in the various tax jurisdictions which the Company operates and less excess tax benefits recognized in the United States in the three and six months ended September 30, 2018. The Company recognized excess tax benefits of $0.7 million and $9.0 million, respectively, at 21% federal corporate income tax rate post the Tax Act in the three and six months ended September 30, 2018. In the same periods in fiscal year 2018, the Company recognized $1.1 million and $11.0 million of excess tax benefits, respectively, at 35% federal corporate income tax rate, after adoption of ASU 2016-09. In the three and six months ended September 30, 2018, there were discrete tax benefits of $0.5 million and $1.4 million, respectively, from the reversal of uncertain tax positions from the expiration of statutes of limitations. In the same periods ended September 30, 2017, the tax benefits from reversal of uncertain tax positions from the expiration of statutes of limitations were $0.7 million and $1.3 million, respectively. As of September 30, 2018 and March 31, 2018, the total amount of unrecognized tax benefits due to uncertain tax positions was $70.4 million and $69.1 million, respectively, all of which would affect the effective income tax rate if recognized. As of September 30, 2018 and March 31, 2018, the Company had $34.5 million and $35.0 million, respectively, in non-current income taxes payable including interest and penalties, related to the Company's income tax liability for uncertain tax positions. The Company recognizes interest and penalties related to unrecognized tax positions in income tax expense. As of September 30, 2018 and March 31, 2018, the Company had $2.5 million and $2.3 million, respectively, of accrued interest and penalties related to uncertain tax positions. Although the Company has adequately provided for uncertain tax positions, the provisions on these positions may change as revised estimates are made or the underlying matters are settled or otherwise resolved. During fiscal year 2019, the Company continues to review its tax positions and provide for or reverse unrecognized tax benefits as issues arise. During the next twelve months, it is reasonably possible that the amount of unrecognized tax benefits could increase or decrease significantly due to changes in tax law in various jurisdictions, new tax audits and changes in the U.S. dollar as compared to other currencies. Excluding these factors, uncertain tax positions may decrease by as much as $3.3 million from the lapse of the statutes of limitations in various jurisdictions during the next twelve months.

Income Taxes

The Company is incorporated in Switzerland but operates in various countries with differing tax laws and rates. Further, a portion of the Company’s income before taxes and the provision for (benefit from) income taxes are generated outside of Switzerland.

The Company has not adjusted the net provisional charge from remeasuring deferred tax assets related to the Tax Cuts and Jobs Act (the "Tax Act") in the United States in fiscal year 2018. The Company continues to refine the estimate based on ongoing analysis and available information and interpretations through the third quarter of fiscal year 2019.

The income tax provision for the three months ended September 30, 2018 was $6.2 million based on an effective income tax rate of 8.8% of pre-tax income, compared to an income tax provision of $4.1 million based on an effective income tax rate of 6.8% of pre-tax income for the three months ended September 30, 2017. The income tax provision for the six months ended September 30, 2018 was $1.0 million based on an effective income tax rate of 1.0% of pre-tax income, compared to an income tax benefit of $1.3 million based on an effective income tax rate of (1.5)% of pre-tax income for the six months ended September 30, 2017.

The changes in the effective income tax rate for the three and six months ended September 30, 2018, compared to the three and six months ended September 30, 2017, were primarily due to the mix of income and losses in the various tax jurisdictions which the Company operates and less excess tax benefits recognized in the United States in the three and six months ended September 30, 2018. The Company recognized excess tax benefits of $0.7 million and $9.0 million, respectively, at 21% federal corporate income tax rate post the Tax Act in the three and six months ended September 30, 2018. In the same periods in fiscal year 2018, the Company recognized $1.1 million and $11.0 million of excess tax benefits, respectively, at 35% federal corporate income tax rate, after adoption of ASU 2016-09. In the three and six months ended September 30, 2018, there were discrete tax benefits of $0.5 million and $1.4 million, respectively, from the reversal of uncertain tax positions from the expiration of statutes of limitations. In the same periods ended September 30, 2017, the tax benefits from reversal of uncertain tax positions from the expiration of statutes of limitations were $0.7 million and $1.3 million, respectively.

As of September 30, 2018 and March 31, 2018, the total amount of unrecognized tax benefits due to uncertain tax positions was $70.4 million and $69.1 million, respectively, all of which would affect the effective income tax rate if recognized.

As of September 30, 2018 and March 31, 2018, the Company had $34.5 million and $35.0 million, respectively, in non-current income taxes payable including interest and penalties, related to the Company's income tax liability for uncertain tax positions.

The Company recognizes interest and penalties related to unrecognized tax positions in income tax expense. As of September 30, 2018 and March 31, 2018, the Company had $2.5 million and $2.3 million, respectively, of accrued interest and penalties related to uncertain tax positions.

Although the Company has adequately provided for uncertain tax positions, the provisions on these positions may change as revised estimates are made or the underlying matters are settled or otherwise resolved. During fiscal year 2019, the Company continues to review its tax positions and provide for or reverse unrecognized tax benefits as issues arise. During the next twelve months, it is reasonably possible that the amount of unrecognized tax benefits could increase or decrease significantly due to changes in tax law in various jurisdictions, new tax audits and changes in the U.S. dollar as compared to other currencies. Excluding these factors, uncertain tax positions may decrease by as much as $3.3 million from the lapse of the statutes of limitations in various jurisdictions during the next twelve months.