Income Taxes	9 Months Ended
Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 9 — Income Taxes The Company calculates its provision for income taxes at the end of each interim reporting period on the basis of an estimated annual effective tax rate adjusted for tax items that are discrete to each period. For the three and nine months ended December 31, 2017, the Company recorded an income tax expense of $2.2 million and an income tax benefit of $18.5 million, respectively, resulting in a negative effective tax rate of 8.8% and an effective tax benefit rate of 26.8%, respectively. The effective tax rates for the periods differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits, offset by additional income tax expense due to the revaluation of net deferred tax assets resulting from the lowering of the corporate federal income tax rate from 35% to 21% under H.R.1, informally known as the Tax Cuts and Jobs Act, which was enacted into law on December 22, 2017 (the Tax Reform). For the three and nine months ended December 31, 2016, the Company recorded an income tax provision of $0.9 million and $5.3 million, respectively, resulting in an effective tax rate of 15.5% and 23.1%, respectively. The effective tax rates for the periods differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits. The effective tax rate for the nine months ended December 31, 2016 also reflects an increase in valuation allowances on state net operating losses and state research and development tax credits. When a reliable estimate of the annual effective tax rate cannot be made, the Company computes its provision for income taxes using the actual effective tax rate method for the year-to-date period. For the three and nine months ended December 31, 2016, the Company used the actual effective tax rate method in calculating the income tax provision for the period as a reliable estimate of the annual effective tax rate could not be made. Future realization of existing deferred tax assets ultimately depends on future profitability and the existence of sufficient taxable income of appropriate character (for example, ordinary income versus capital gains) within the carryforward period available under tax law. In the event that the Company’s estimate of taxable income is less than that required to utilize the full amount of any deferred tax asset, a valuation allowance is established, which would cause a decrease to income in the period such determination is made. For the three and nine months ended December 31, 2017, the Company’s gross unrecognized tax benefits increased by $1.1 million and $3.5 million, respectively. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly. In accordance with the ASU 2016-09, which the Company adopted during the first quarter of fiscal year 2018, the Company recorded a cumulative effect adjustment as of the beginning of the first quarter of fiscal year 2018 to increase retained earnings by $58.7 million with a corresponding increase to deferred tax assets to recognize net operating loss carryforwards attributable to excess tax benefits on share-based compensation that had not been previously recognized. On a prospective basis, the Company recognizes excess tax benefits or deficiencies on vesting or settlement of awards as discrete items within income tax benefit or provision within net income (loss) and the related cash flows classified within operating activities. *U.S. Tax Reform* On December 22, 2017, the Tax Reform was enacted into law. Among other matters, the Tax Reform lowered the corporate federal income tax rate from 35% to 21%, effective January 1, 2018, and transitions U.S. international taxation from a worldwide tax system to a territorial tax system. As the Company has a March 31 fiscal year-end, the lower corporate federal income tax rate will be phased in, resulting in a U.S. statutory federal rate of approximately 31.6% for fiscal year 2018, and 21.0% for subsequent fiscal years. ASC 740-10, Income Taxes, requires the Company to recognize the effect of any tax laws during the period in which they are enacted. Accordingly, the Company performed preliminary calculations and, based on the estimated effect of the reduction in the corporate federal income tax rate under the Tax Reform, the Company reduced net deferred tax assets, which reduction was recognized as additional income tax expense of $12.2 million for the three and nine months ended December 31, 2017. The Company has performed a preliminary review of the other provisions in the Tax Reform, including U.S. tax on unrepatriated foreign earnings, and has preliminarily concluded that they have no material impact on the Company’s consolidated financial statements or ability to realize its deferred tax assets. The Company continues to evaluate the global tax implications of the Tax Reform. The final impact of the Tax Reform may differ from the above estimate due to, among other things, changes in interpretation, the issuance of additional guidance and any updates to estimates the Company utilized to calculate the transition impacts. The Securities and Exchange Commission has issued rules under SAB 118 that allow for a measurement period of up to one year after the enactment date of the Tax Reform to finalize the recording of the related tax impacts. The Company currently anticipates finalizing and recording any resulting adjustments by the end of the quarter ending December 31, 2018.

Note 9 — Income Taxes

The Company calculates its provision for income taxes at the end of each interim reporting period on the basis of an estimated annual effective tax rate adjusted for tax items that are discrete to each period.

For the three and nine months ended December 31, 2017, the Company recorded an income tax expense of $2.2 million and an income tax benefit of $18.5 million, respectively, resulting in a negative effective tax rate of 8.8% and an effective tax benefit rate of 26.8%, respectively. The effective tax rates for the periods differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits, offset by additional income tax expense due to the revaluation of net deferred tax assets resulting from the lowering of the corporate federal income tax rate from 35% to 21% under H.R.1, informally known as the Tax Cuts and Jobs Act, which was enacted into law on December 22, 2017 (the Tax Reform).

For the three and nine months ended December 31, 2016, the Company recorded an income tax provision of $0.9 million and $5.3 million, respectively, resulting in an effective tax rate of 15.5% and 23.1%, respectively. The effective tax rates for the periods differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits. The effective tax rate for the nine months ended December 31, 2016 also reflects an increase in valuation allowances on state net operating losses and state research and development tax credits.

When a reliable estimate of the annual effective tax rate cannot be made, the Company computes its provision for income taxes using the actual effective tax rate method for the year-to-date period. For the three and nine months ended December 31, 2016, the Company used the actual effective tax rate method in calculating the income tax provision for the period as a reliable estimate of the annual effective tax rate could not be made.

Future realization of existing deferred tax assets ultimately depends on future profitability and the existence of sufficient taxable income of appropriate character (for example, ordinary income versus capital gains) within the carryforward period available under tax law. In the event that the Company’s estimate of taxable income is less than that required to utilize the full amount of any deferred tax asset, a valuation allowance is established, which would cause a decrease to income in the period such determination is made.

For the three and nine months ended December 31, 2017, the Company’s gross unrecognized tax benefits increased by $1.1 million and $3.5 million, respectively. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly.

In accordance with the ASU 2016-09, which the Company adopted during the first quarter of fiscal year 2018, the Company recorded a cumulative effect adjustment as of the beginning of the first quarter of fiscal year 2018 to increase retained earnings by $58.7 million with a corresponding increase to deferred tax assets to recognize net operating loss carryforwards attributable to excess tax benefits on share-based compensation that had not been previously recognized. On a prospective basis, the Company recognizes excess tax benefits or deficiencies on vesting or settlement of awards as discrete items within income tax benefit or provision within net income (loss) and the related cash flows classified within operating activities.

U.S. Tax Reform

On December 22, 2017, the Tax Reform was enacted into law. Among other matters, the Tax Reform lowered the corporate federal income tax rate from 35% to 21%, effective January 1, 2018, and transitions U.S. international taxation from a worldwide tax system to a territorial tax system. As the Company has a March 31 fiscal year-end, the lower corporate federal income tax rate will be phased in, resulting in a U.S. statutory federal rate of approximately 31.6% for fiscal year 2018, and 21.0% for subsequent fiscal years.

ASC 740-10, Income Taxes, requires the Company to recognize the effect of any tax laws during the period in which they are enacted. Accordingly, the Company performed preliminary calculations and, based on the estimated effect of the reduction in the corporate federal income tax rate under the Tax Reform, the Company reduced net deferred tax assets, which reduction was recognized as additional income tax expense of $12.2 million for the three and nine months ended December 31, 2017. The Company has performed a preliminary review of the other provisions in the Tax Reform, including U.S. tax on unrepatriated foreign earnings, and has preliminarily concluded that they have no material impact on the Company’s consolidated financial statements or ability to realize its deferred tax assets. The Company continues to evaluate the global tax implications of the Tax Reform.

The final impact of the Tax Reform may differ from the above estimate due to, among other things, changes in interpretation, the issuance of additional guidance and any updates to estimates the Company utilized to calculate the transition impacts. The Securities and Exchange Commission has issued rules under SAB 118 that allow for a measurement period of up to one year after the enactment date of the Tax Reform to finalize the recording of the related tax impacts. The Company currently anticipates finalizing and recording any resulting adjustments by the end of the quarter ending December 31, 2018.