Income Taxes	9 Months Ended
Dec. 31, 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 and nine months ended December 31, 2018, the Company recorded an income tax expense of $3.2 million and an income tax benefit of $35.7 million, respectively, resulting in a negative effective tax rate of 36% and an effective tax benefit rate of 32%, 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 an increase in valuation allowances on state net operating losses and state research and development tax credits. 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 9% and an effective tax benefit rate of 27%, 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). 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, 2018, the Company’s gross unrecognized tax benefits decreased by an insignificant amount and increased by $5.1 million, respectively. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly. 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 Securities and Exchange Commission issued rules under SAB 118 that allowed for a measurement period of up to one year after the enactment date of the Tax Reform to finalize the recording of the related enactment-date tax impacts. The Company finalized its accounting for the related enactment-date tax impacts during the three and nine months ended December 31, 2018 with no adjustments to the provisional estimate recorded at December 31, 2017. For the three and nine months ended December 31, 2018, the Company has accounted for the fiscal year 2019 impacts of the Tax Reform in its (provision for) benefit from income taxes in accordance with its interpretation of the Tax Reform and available guidance. However, additional Treasury regulations and other interpretive guidance are expected. The impact of any additional guidance will be recorded in the subsequent periods in which the additional guidance is released.

Income Taxes

9 Months Ended

Dec. 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, 2018, the Company recorded an income tax expense of $3.2 million and an income tax benefit of $35.7 million, respectively, resulting in a negative effective tax rate of 36% and an effective tax benefit rate of 32%, 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 an increase in valuation allowances on state net operating losses and state research and development tax credits.

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 9% and an effective tax benefit rate of 27%, 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).

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, 2018, the Company’s gross unrecognized tax benefits decreased by an insignificant amount and increased by $5.1 million, respectively. In the next 12 months it is reasonably possible that the amount of unrecognized tax benefits will not change significantly.

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 Securities and Exchange Commission issued rules under SAB 118 that allowed for a measurement period of up to one year after the enactment date of the Tax Reform to finalize the recording of the related enactment-date tax impacts. The Company finalized its accounting for the related enactment-date tax impacts during the three and nine months ended December 31, 2018 with no adjustments to the provisional estimate recorded at December 31, 2017. For the three and nine months ended December 31, 2018, the Company has accounted for the fiscal year 2019 impacts of the Tax Reform in its (provision for) benefit from income taxes in accordance with its interpretation of the Tax Reform and available guidance. However, additional Treasury regulations and other interpretive guidance are expected. The impact of any additional guidance will be recorded in the subsequent periods in which the additional guidance is released.