Income Taxes	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective income tax rate was 15.4% and 32.3% for the three months ended March 31, 2018 and 2017, respectively. The decrease was primarily due to a lower U.S. effective tax rate, as a result of U.S. tax reform, changes in pretax income mix across jurisdictions with disparate tax rates, excess tax deductions on stock based compensation, R&D credits and a release of reserves for uncertain tax positions, partially offset by an increase in current year accruals for uncertain tax positions. The total amount of unrecognized tax benefits as of March 31, 2018 was $11.8 million, of which $10.3 million would affect our effective tax rate if recognized. It is reasonably possible that approximately $3.7 million of our unrecognized tax benefits as of March 31, 2018 will reverse within the next twelve months. We recognize interest and penalties related to unrecognized tax benefits through income tax expense. As of March 31, 2018, we had $0.7 million accrued for the payment of interest. We are subject to taxation in the U.S. and various state and foreign jurisdictions. With few exceptions, we are no longer subject to examinations by tax authorities for years prior to 2013.

Income Taxes

3 Months Ended

Mar. 31, 2018

Our effective income tax rate was 15.4% and 32.3% for the three months ended March 31, 2018 and 2017, respectively. The decrease was primarily due to a lower U.S. effective tax rate, as a result of U.S. tax reform, changes in pretax income mix across jurisdictions with disparate tax rates, excess tax deductions on stock based compensation, R&D credits and a release of reserves for uncertain tax positions, partially offset by an increase in current year accruals for uncertain tax positions.

The total amount of unrecognized tax benefits as of March 31, 2018 was $11.8 million, of which $10.3 million would affect our effective tax rate if recognized. It is reasonably possible that approximately $3.7 million of our unrecognized tax benefits as of March 31, 2018 will reverse within the next twelve months.

We recognize interest and penalties related to unrecognized tax benefits through income tax expense. As of March 31, 2018, we had $0.7 million accrued for the payment of interest.

We are subject to taxation in the U.S. and various state and foreign jurisdictions. With few exceptions, we are no longer subject to examinations by tax authorities for years prior to 2013.