Income Taxes	3 Months Ended
Mar. 31, 2019
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Taxes	Income Taxes The Company applied an estimated annual effective tax rate (“ETR”) approach for calculating a tax provision for interim periods. The Company recorded a provision for income taxes of $39 thousand and $85 thousand for the three months ended March 31, 2019 and 2018, respectively. The Company’s ETR was (0.2)% and (0.4)% for the three months ended March 31, 2019, and 2018, respectively. The Company’s ETR for the three months ended March 31, 2019 differs from the U.S. federal statutory tax rate of 21% primarily as a result of nondeductible expenses (including the Nellix contingently issuable common stock), state income taxes, foreign income taxes, and the impact of a full valuation allowance on its deferred tax assets. The Company has evaluated the available evidence supporting the realization of its deferred tax assets, including the amount and timing of future taxable income, and has determined that it is more likely than not that the domestic and foreign deferred tax assets will not be realized. Due to such uncertainties surrounding the realization of the domestic and foreign deferred tax assets, the Company maintained a valuation allowance of $135.2 million against a substantial portion of its deferred tax assets as of March 31, 2019. If and when the Company determines that it will be able to realize some portion or all of its deferred tax assets, an adjustment to its valuation allowance on its deferred tax assets would have the effect of increasing net income in the period(s) such determination is made.

Income Taxes

The Company applied an estimated annual effective tax rate (“ETR”) approach for calculating a tax provision for interim periods. The Company recorded a provision for income taxes of $39 thousand and $85 thousand for the three months ended March 31, 2019 and 2018, respectively. The Company’s ETR was (0.2)% and (0.4)% for the three months ended March 31, 2019, and 2018, respectively. The Company’s ETR for the three months ended March 31, 2019 differs from the U.S. federal statutory tax rate of 21% primarily as a result of nondeductible expenses (including the Nellix contingently issuable common stock), state income taxes, foreign income taxes, and the impact of a full valuation allowance on its deferred tax assets.

The Company has evaluated the available evidence supporting the realization of its deferred tax assets, including the amount and timing of future taxable income, and has determined that it is more likely than not that the domestic and foreign deferred tax assets will not be realized. Due to such uncertainties surrounding the realization of the domestic and foreign deferred tax assets, the Company maintained a valuation allowance of $135.2 million against a substantial portion of its deferred tax assets as of March 31, 2019. If and when the Company determines that it will be able to realize some portion or all of its deferred tax assets, an adjustment to its valuation allowance on its deferred tax assets would have the effect of increasing net income in the period(s) such determination is made.