Income Taxes	3 Months Ended
Jun. 30, 2018
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 months ended June 30, 2018, the Company recorded an income tax benefit of $29.2 million resulting in an effective tax benefit rate of 44.4%. The effective tax benefit rate in the first quarter of fiscal year 2019 differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits, offset by increases in valuation allowances on state net operating losses and state research and development tax credits. For the three months ended June 30, 2017, the Company recorded an income tax benefit of $9.2 million, resulting in an effective tax benefit rate of 51.2%. The effective tax benefit rate in the first quarter of fiscal year 2018 was higher than the U.S. statutory rate due primarily to the benefit of research and development tax credit offset by increases in valuation allowances on state net operating losses and state research and development tax credits. 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 months ended June 30, 2018, the Company’s gross unrecognized tax benefits increased by $5.4 million. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly. On December 22, 2017, H.R. 1, informally known as the Tax Cuts and Jobs Acts (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 transitioned U.S. international taxation from a worldwide tax system to a modified territorial tax system. The Company has estimated the impact of the Tax Reform in its fiscal year 2018 benefit from (provision for) income taxes in accordance with its interpretation of the Tax Reform and available guidance. The Tax Reform resulted in a provisional income tax expense related to the remeasurement of the Company’s net deferred tax assets recorded in the third quarter of fiscal year 2018. As of June 30, 2018, the Company has not finalized the accounting for the tax effects of the Tax Reform and has not made any adjustments related to the provisional estimate during the three months ended June 30, 2018. 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 provisional 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 within the year measurement period.

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 months ended June 30, 2018, the Company recorded an income tax benefit of $29.2 million resulting in an effective tax benefit rate of 44.4%. The effective tax benefit rate in the first quarter of fiscal year 2019 differed from the U.S. statutory rate due primarily to the benefit of research and development tax credits, offset by increases in valuation allowances on state net operating losses and state research and development tax credits.

For the three months ended June 30, 2017, the Company recorded an income tax benefit of $9.2 million, resulting in an effective tax benefit rate of 51.2%. The effective tax benefit rate in the first quarter of fiscal year 2018 was higher than the U.S. statutory rate due primarily to the benefit of research and development tax credit offset by increases in valuation allowances on state net operating losses and state research and development tax credits.

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 months ended June 30, 2018, the Company’s gross unrecognized tax benefits increased by $5.4 million. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly.

On December 22, 2017, H.R. 1, informally known as the Tax Cuts and Jobs Acts (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 transitioned U.S. international taxation from a worldwide tax system to a modified territorial tax system.

The Company has estimated the impact of the Tax Reform in its fiscal year 2018 benefit from (provision for) income taxes in accordance with its interpretation of the Tax Reform and available guidance. The Tax Reform resulted in a provisional income tax expense related to the remeasurement of the Company’s net deferred tax assets recorded in the third quarter of fiscal year 2018. As of June 30, 2018, the Company has not finalized the accounting for the tax effects of the Tax Reform and has not made any adjustments related to the provisional estimate during the three months ended June 30, 2018.

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 provisional 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 within the year measurement period.