Income Taxes	6 Months Ended
Sep. 30, 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 six months ended September 30, 2017, the Company recorded an income tax benefit of $11.5 million and $20.6 million, respectively, resulting in an effective tax benefit rate of 43.9% and 46.9%, respectively. For the three and six months ended September 30, 2016, the Company recorded an income tax provision of $3.6 million and $4.4 million, respectively, resulting in an effective tax rate of 25.1% and 25.5%, 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 six months ended September 30, 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 six months ended September 30, 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 six months ended September 30, 2017, the Company’s gross unrecognized tax benefits increased by $1.2 million and $2.4 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.

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 six months ended September 30, 2017, the Company recorded an income tax benefit of $11.5 million and $20.6 million, respectively, resulting in an effective tax benefit rate of 43.9% and 46.9%, respectively. For the three and six months ended September 30, 2016, the Company recorded an income tax provision of $3.6 million and $4.4 million, respectively, resulting in an effective tax rate of 25.1% and 25.5%, 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 six months ended September 30, 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 six months ended September 30, 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 six months ended September 30, 2017, the Company’s gross unrecognized tax benefits increased by $1.2 million and $2.4 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.