Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective tax rate for the three and nine months ended September 30, 2018 was a negative rate of 4% and 4% compared to positive rate of 20% and 29% for the same periods of 2017. Our effective tax rate was impacted primarily by a $2.3 million tax benefit for the release of valuation allowance during the three and nine months ended September 30, 2018, related to acquired intangibles for which we had no tax basis, partially offset by state and foreign tax expense. We maintain a full valuation allowance against our net deferred tax assets as of September 30, 2018 based on our assessment that it is not more likely than not these future benefits will be realized before expiration. We made provisional estimates related to certain provisions of the Tax Cuts and Jobs Act of 2017 in the fourth quarter of 2017, including a reduction in our net deferred tax assets by $105.7 million offset by an increase in the valuation allowance related to the revaluation of our net deferred tax assets from 35% to 21%, and a zero transition tax on the mandatory deemed repatriation of foreign earnings due to our estimated net deficit in foreign earnings of $41.2 million at December 31, 2017. Additional work is necessary to finalize the calculation of our gross balances of U.S. deferred tax assets and liabilities, as well as the analysis of our net deficit in foreign earnings in connection with the transition tax. Any subsequent adjustment to these amounts is expected to have no tax effect due to our valuation allowance against net deferred tax assets. This analysis will be completed by the fourth quarter of 2018.

Income Taxes

Our effective tax rate for the three and nine months ended September 30, 2018 was a negative rate of 4% and 4% compared to positive rate of 20% and 29% for the same periods of 2017. Our effective tax rate was impacted primarily by a $2.3 million tax benefit for the release of valuation allowance during the three and nine months ended September 30, 2018, related to acquired intangibles for which we had no tax basis, partially offset by state and foreign tax expense.

We maintain a full valuation allowance against our net deferred tax assets as of September 30, 2018 based on our assessment that it is not more likely than not these future benefits will be realized before expiration.

We made provisional estimates related to certain provisions of the Tax Cuts and Jobs Act of 2017 in the fourth quarter of 2017, including a reduction in our net deferred tax assets by $105.7 million offset by an increase in the valuation allowance related to the revaluation of our net deferred tax assets from 35% to 21%, and a zero transition tax on the mandatory deemed repatriation of foreign earnings due to our estimated net deficit in foreign earnings of $41.2 million at December 31, 2017. Additional work is necessary to finalize the calculation of our gross balances of U.S. deferred tax assets and liabilities, as well as the analysis of our net deficit in foreign earnings in connection with the transition tax. Any subsequent adjustment to these amounts is expected to have no tax effect due to our valuation allowance against net deferred tax assets. This analysis will be completed by the fourth quarter of 2018.