Income Taxes	3 Months Ended
Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We file income tax returns for federal purposes and in many states, as well as in multiple foreign jurisdictions. Our tax filings remain subject to examination by applicable tax authorities for a certain length of time, generally three to four years, following the tax year to which these filings relate. Our U.S. federal income tax return for fiscal year 2016 is currently under audit by the Internal Revenue Service. Deferred Tax Assets Net deferred income tax assets at March 31, 2019, primarily include R&D tax credits, stock-based compensation expense, deferred revenue, accruals and reserves, and net operating losses, partially offset by accelerated depreciation expense and valuation allowance reserve. Our total net deferred tax assets at March 31, 2019 were $18.8 million. In preparing our condensed consolidated financial statements, management assesses the likelihood that its deferred tax assets will be realized from future taxable income. In evaluating our ability to recover our deferred income tax assets, management considers all available positive and negative evidence, including our operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction by jurisdiction basis. A valuation allowance is established if it is determined that it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Management exercises significant judgment in determining our provisions for income taxes, our deferred tax assets and liabilities, and our future taxable income for purposes of assessing our ability to utilize any future tax benefit from our deferred tax assets. As of March 31, 2019, we continue to demonstrate three-year cumulative pre-tax income in the U.S. federal and state tax jurisdictions; however, we have Arizona R&D Tax Credits expiring unutilized each year. Therefore, management has concluded that it is more likely than not that our Arizona R&D deferred tax asset will not be realized. As of March 31, 2019, we have cumulative pre-tax losses in Australia, the U.K., and Canada, which limits the ability to consider other subjective evidence, such as projections for future growth. On the basis of this evaluation, a full valuation allowance has been recorded for these jurisdictions. The amount of the deferred tax asset considered realizable; however, could be adjusted in future periods if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as projections for growth. We complete R&D tax credit studies for each year that an R&D tax credit is claimed for federal, Arizona, and California income tax purposes. Management has made the determination that it is more likely than not that the full benefit of the R&D tax credit will not be sustained on examination and recorded a liability for unrecognized tax benefits of $5.7 million as of March 31, 2019. In addition, management accrued $0.1 million for estimated uncertain tax positions related to certain federal income tax liabilities. Should the unrecognized benefit of $5.7 million be recognized, our effective tax rate would be favorably impacted. Approximately $2.7 million of the unrecognized tax benefit associated with R&D credits has been netted against the R&D deferred tax asset. Effective Tax Rate Our overall effective tax rate for the three months ended March 31, 2019, after discrete period adjustments, was (28.8)%. Before discrete adjustments, the tax rate was 21.1%, which is greater than the federal statutory rate, primarily due to state taxes and non-deductible expenses for items such as meals and entertainment, executive compensation limitation under Internal Revenue Code ("IRC") Section 162(m), lobbying fees, and an income inclusion from global intangible low-taxed income ("GILTI"), offset by a reduction for foreign-derived intangible income ("FDII") and R&D tax credits. The effective tax rate was favorably impacted by a $2.7 million discrete tax benefit primarily associated with windfalls related to stock-based compensation for RSUs that vested or stock options that were exercised during the three months ended March 31, 2019. This was offset by an unfavorable discrete item of $0.3 million related to the write off of certain deferred tax assets related to future stock compensation vests for certain officers for whom deductibility of compensation is limited by IRC Section 162(m).

Income Taxes

We file income tax returns for federal purposes and in many states, as well as in multiple foreign jurisdictions. Our tax filings remain subject to examination by applicable tax authorities for a certain length of time, generally three to four years, following the tax year to which these filings relate. Our U.S. federal income tax return for fiscal year 2016 is currently under audit by the Internal Revenue Service.

Deferred Tax Assets

Net deferred income tax assets at March 31, 2019, primarily include R&D tax credits, stock-based compensation expense, deferred revenue, accruals and reserves, and net operating losses, partially offset by accelerated depreciation expense and valuation allowance reserve. Our total net deferred tax assets at March 31, 2019 were $18.8 million.

In preparing our condensed consolidated financial statements, management assesses the likelihood that its deferred tax assets will be realized from future taxable income. In evaluating our ability to recover our deferred income tax assets, management considers all available positive and negative evidence, including our operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction by jurisdiction basis. A valuation allowance is established if it is determined that it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Management exercises significant judgment in determining our provisions for income taxes, our deferred tax assets and liabilities, and our future taxable income for purposes of assessing our ability to utilize any future tax benefit from our deferred tax assets.

As of March 31, 2019, we continue to demonstrate three-year cumulative pre-tax income in the U.S. federal and state tax jurisdictions; however, we have Arizona R&D Tax Credits expiring unutilized each year. Therefore, management has concluded that it is more likely than not that our Arizona R&D deferred tax asset will not be realized.

As of March 31, 2019, we have cumulative pre-tax losses in Australia, the U.K., and Canada, which limits the ability to consider other subjective evidence, such as projections for future growth. On the basis of this evaluation, a full valuation allowance has been recorded for these jurisdictions. The amount of the deferred tax asset considered realizable; however, could be adjusted in future periods if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as projections for growth.

We complete R&D tax credit studies for each year that an R&D tax credit is claimed for federal, Arizona, and California income tax purposes. Management has made the determination that it is more likely than not that the full benefit of the R&D tax credit will not be sustained on examination and recorded a liability for unrecognized tax benefits of $5.7 million as of March 31, 2019. In addition, management accrued $0.1 million for estimated uncertain tax positions related to certain federal income tax liabilities. Should the unrecognized benefit of $5.7 million be recognized, our effective tax rate would be favorably impacted. Approximately $2.7 million of the unrecognized tax benefit associated with R&D credits has been netted against the R&D deferred tax asset.

Effective Tax Rate

Our overall effective tax rate for the three months ended March 31, 2019, after discrete period adjustments, was (28.8)%. Before discrete adjustments, the tax rate was 21.1%, which is greater than the federal statutory rate, primarily due to state taxes and non-deductible expenses for items such as meals and entertainment, executive compensation limitation under Internal Revenue Code ("IRC") Section 162(m), lobbying fees, and an income inclusion from global intangible low-taxed income ("GILTI"), offset by a reduction for foreign-derived intangible income ("FDII") and R&D tax credits. The effective tax rate was favorably impacted by a $2.7 million discrete tax benefit primarily associated with windfalls related to stock-based compensation for RSUs that vested or stock options that were exercised during the three months ended March 31, 2019. This was offset by an unfavorable discrete item of $0.3 million related to the write off of certain deferred tax assets related to future stock compensation vests for certain officers for whom deductibility of compensation is limited by IRC Section 162(m).