Income Taxes	9 Months Ended
Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For interim periods, the income tax provision is comprised of tax on ordinary income provided at the most recent estimated annual effective tax rate, adjusted for the tax effect of discrete items. We use an estimated annual effective tax rate which is based on expected annual income and statutory tax rates to determine our quarterly provision for income taxes. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter. Our provision for (benefit from) income taxes for the three and nine months ended September 30, 2019 was $(1.6) million and $1.9 million, respectively, representing a quarterly effective income tax rate of (25)% for the three months ended September 30, 2019 and a year to date effective income tax rate of 11%. We recorded a tax benefit in the third quarter of 2019 due to a $2.8 million discrete tax benefit related to a Research and Development tax credit for the years 2010 to 2018. The effective income tax rate for the full year 2018 was 0% due to the availability of net operating loss carryforwards. A valuation allowance of $37.6 million was recorded against our net deferred tax assets of approximately $44.4 million as of September 30, 2019.

Income Taxes

For interim periods, the income tax provision is comprised of tax on ordinary income provided at the most recent estimated annual effective tax rate, adjusted for the tax effect of discrete items. We use an estimated annual effective tax rate which is based on expected annual income and statutory tax rates to determine our quarterly provision for income taxes. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter.

Our provision for (benefit from) income taxes for the three and nine months ended September 30, 2019 was $(1.6) million and $1.9 million, respectively, representing a quarterly effective income tax rate of (25)% for the three months ended September 30, 2019 and a year to date effective income tax rate of 11%. We recorded a tax benefit in the third quarter of 2019 due to a $2.8 million discrete tax benefit related to a Research and Development tax credit for the years 2010 to 2018. The effective income tax rate for the full year 2018 was 0% due to the availability of net operating loss carryforwards. A valuation allowance of $37.6 million was recorded against our net deferred tax assets of approximately $44.4 million as of September 30, 2019.