Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes The Company recorded an income tax provision of $0.1 million and $27,000 for the three months ended September 30, 2018 and 2017, respectively. The Company recorded an income tax benefit of $0.1 million and $0.3 million for the nine months ended September 30, 2018 and 2017, respectively. The income tax benefit for the three and nine months ended September 30, 2018 consisted primarily of a credit to foreign jurisdiction. As of September 30, 2018, based on the available objective evidence, management believes it is more likely than not that the net deferred tax assets will not be realized for federal and state purposes. Accordingly, management has applied a full valuation allowance against its federal and state net deferred tax assets as of September 30, 2018. A release of such valuation allowance could cause a material increase to income in the period such determination is made. Internal Revenue Code Section 382 and similar California rules place a limitation on the amount of taxable income that can be offset by NOL carryforwards after a change in control (generally greater than 50% change in ownership). Generally, after a control change, a corporation cannot deduct NOL carryforwards in excess of the Section 382 limitations. Due to these provisions, utilization of NOL and tax credit carryforwards may be subject to annual limitations regarding their utilization against taxable income in future periods. The Company completed Section 382 analysis in 2016 and determined ownership changes occurred in July 2005, November 2009 and August 2017, which resulted in reductions to the U.S. federal and California net operating losses of $34.9 million and $24.1 million, respectively, and U.S. federal research and development credits by $1.8 million. Since no deferred tax assets have been recognized on our balance sheet related to our NOLs and tax credits, as they are fully reserved by a valuation allowance, there was no impact to the tax provision. On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Act”). The Act makes broad and complex changes to the U.S. tax code including, but not limited to: (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) requiring current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations; (5) eliminating the corporate alternative minimum tax, or AMT, and changing how existing AMT credits can be realized; (6) creating the base erosion anti-abuse tax, or BEAT, a new minimum tax; (7) creating a new limitation on deductible interest expense; and (8) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. As of December 31, 2017, the Company’s remeasured certain deferred tax assets and liabilities based on rates at which they are expected to reverse in the future, which is generally 21%. The rate reduction would generally take effect on January 1, 2018. Consequently, any changes in the U.S. corporate income tax rate will impact the carrying value of the deferred tax assets. Under the new corporate income tax rate of 21%, U.S. federal and state deferred tax assets decreased by approximately $15.7 million as of December 31, 2017 and the valuation allowance decreased by approximately the same amount. Due to the valuation allowance on the deferred tax assets, the provisional amount recorded related to the remeasurement was zero. As of December 31, 2017, the Company's foreign subsidiaries are in a cumulative deficit. Therefore, the one-time transition tax on deemed repatriation of previously untaxed accumulated earnings and profits of foreign subsidiaries has minimal impact on the Company. Undistributed earnings of foreign subsidiaries are determined to be reinvested indefinitely. Accounting for the transition tax and the conclusion on the Company’s indefinite reinvestment have been completed pursuant to the requirements of the Act. The SEC staff issued Staff Accountant Bulletin No. 118, or SAB 118, which provides guidance on accounting for the tax effects of the Act. SAB 118 provides a measurement period that should not extend beyond one year from the Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Act. As noted above, the Company has recorded a provisional amount associated with the deferred tax assets and related valuation allowance as of September 30, 2018. At September 30, 2018, the Company is still analyzing certain aspects of the Act including (a) provisions for Global Intangible Low-Taxed Income, or GILTI, wherein taxes on foreign income are imposed in excess of a deemed return on tangible assets of foreign corporations (including related accounting policy elections) and (b) state tax implications of the Act.

9. Income Taxes

The Company recorded an income tax provision of $0.1 million and $27,000 for the three months ended September 30, 2018 and 2017, respectively. The Company recorded an income tax benefit of $0.1 million and $0.3 million for the nine months ended September 30, 2018 and 2017, respectively. The income tax benefit for the three and nine months ended September 30, 2018 consisted primarily of a credit to foreign jurisdiction.

As of September 30, 2018, based on the available objective evidence, management believes it is more likely than not that the net deferred tax assets will not be realized for federal and state purposes. Accordingly, management has applied a full valuation allowance against its federal and state net deferred tax assets as of September 30, 2018. A release of such valuation allowance could cause a material increase to income in the period such determination is made.

Internal Revenue Code Section 382 and similar California rules place a limitation on the amount of taxable income that can be offset by NOL carryforwards after a change in control (generally greater than 50% change in ownership). Generally, after a control change, a corporation cannot deduct NOL carryforwards in excess of the Section 382 limitations. Due to these provisions, utilization of NOL and tax credit carryforwards may be subject to annual limitations regarding their utilization against taxable income in future periods. The Company completed Section 382 analysis in 2016 and determined ownership changes occurred in July 2005, November 2009 and August 2017, which resulted in reductions to the U.S. federal and California net operating losses of $34.9 million and $24.1 million, respectively, and U.S. federal research and development credits by $1.8 million. Since no deferred tax assets have been recognized on our balance sheet related to our NOLs and tax credits, as they are fully reserved by a valuation allowance, there was no impact to the tax provision.

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Act”). The Act makes broad and complex changes to the U.S. tax code including, but not limited to: (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) requiring current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations; (5) eliminating the corporate alternative minimum tax, or AMT, and changing how existing AMT credits can be realized; (6) creating the base erosion anti-abuse tax, or BEAT, a new minimum tax; (7) creating a new limitation on deductible interest expense; and (8) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017.

As of December 31, 2017, the Company’s remeasured certain deferred tax assets and liabilities based on rates at which they are expected to reverse in the future, which is generally 21%. The rate reduction would generally take effect on January 1, 2018. Consequently, any changes in the U.S. corporate income tax rate will impact the carrying value of the deferred tax assets. Under the new corporate income tax rate of 21%, U.S. federal and state deferred tax assets decreased by approximately $15.7 million as of December 31, 2017 and the valuation allowance decreased by approximately the same amount. Due to the valuation allowance on the deferred tax assets, the provisional amount recorded related to the remeasurement was zero.

As of December 31, 2017, the Company's foreign subsidiaries are in a cumulative deficit. Therefore, the one-time transition tax on deemed repatriation of previously untaxed accumulated earnings and profits of foreign subsidiaries has minimal impact on the Company. Undistributed earnings of foreign subsidiaries are determined to be reinvested indefinitely. Accounting for the transition tax and the conclusion on the Company’s indefinite reinvestment have been completed pursuant to the requirements of the Act.

The SEC staff issued Staff Accountant Bulletin No. 118, or SAB 118, which provides guidance on accounting for the tax effects of the Act. SAB 118 provides a measurement period that should not extend beyond one year from the Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Act. As noted above, the Company has recorded a provisional amount associated with the deferred tax assets and related valuation allowance as of September 30, 2018. At September 30, 2018, the Company is still analyzing certain aspects of the Act including (a) provisions for Global Intangible Low-Taxed Income, or GILTI, wherein taxes on foreign income are imposed in excess of a deemed return on tangible assets of foreign corporations (including related accounting policy elections) and (b) state tax implications of the Act.