Income Tax Expense	3 Months Ended
Mar. 31, 2018
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Tax Expense	Income Tax Expense 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 $0.1 million and $0.2 million for the three months ended March 31, 2018 and 2017, respectively. The Company's ETR was (0.4)% and (0.7)% for the three months ended March 31, 2018, and 2017, respectively. The Company's ETR for the three months ended March 31, 2018 differs from the U.S. federal statutory tax rate of 21% primarily as a result of nondeductible expenses (including the Nellix Contingent Payment), 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 its net deferred tax assets will not be realized in the U.S. and certain foreign jurisdictions. Due to uncertainties surrounding the realization of the deferred tax assets, the Company maintains a full valuation allowance against substantially all deferred tax assets. If/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. On December 22, 2017, the President of the United States signed into law reforms of the US tax code (the “Tax Reform Act”). The legislation significantly changes US tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. The Company recorded provisional amounts as of December 31, 2017 related to the Tax Reform Act under guidance set forth in Staff Accounting Bulletin No. 118 ("SAB 118"). These amounts have not been adjusted as of March 31, 2018, and the Company will continue to monitor any changes to the provisional amounts during the measurement period or until the accounting is complete. However, the Company does not anticipate any material impact to the financial statement due to the full valuation allowance.

Income Tax Expense

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 $0.1 million and $0.2 million for the three months ended March 31, 2018 and 2017, respectively. The Company's ETR was (0.4)% and (0.7)% for the three months ended March 31, 2018, and 2017, respectively. The Company's ETR for the three months ended March 31, 2018 differs from the U.S. federal statutory tax rate of 21% primarily as a result of nondeductible expenses (including the Nellix Contingent Payment), 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 its net deferred tax assets will not be realized in the U.S. and certain foreign jurisdictions. Due to uncertainties surrounding the realization of the deferred tax assets, the Company maintains a full valuation allowance against substantially all deferred tax assets. If/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.

On December 22, 2017, the President of the United States signed into law reforms of the US tax code (the “Tax Reform Act”). The legislation significantly changes US tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective January 1, 2018. The Company recorded provisional amounts as of December 31, 2017 related to the Tax Reform Act under guidance set forth in Staff Accounting Bulletin No. 118 ("SAB 118"). These amounts have not been adjusted as of March 31, 2018, and the Company will continue to monitor any changes to the provisional amounts during the measurement period or until the accounting is complete. However, the Company does not anticipate any material impact to the financial statement due to the full valuation allowance.