Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Act was signed into law, most provisions of which became effective starting in 2018, including the reduction of the statutory corporate income tax rate from 35% to 21%. As of September 30, 2018, the Company has not completed the accounting for the tax effects of enactment of the Tax Act; however, in the fourth quarter of 2017, the Company made a reasonable estimate of the effects on the existing deferred tax balances and the one-time transition tax. No adjustments to the provisional amounts recorded in the fourth quarter of 2017 were made during the three and nine months ended September 30, 2018, respectively. For the nine months ended September 30, 2018, the Company assessed the effect of certain international provisions of the Tax Act that became effective January 1, 2018, and determined that these provisions had an immaterial impact; therefore, the Company did not record any impact as a result of the assessment. The Company will continue to analyze the provision for income taxes under the Tax Act as future guidance is issued. Any revisions will be treated in accordance with the measurement period guidance outlined in SEC Staff Accounting Bulletin No. 118. The Company generally provides for income taxes in interim periods based on the estimated annual effective tax rate for the year, adjusting for discrete items in the quarter in which they arise. The annual effective tax rate before discrete items was 19.0% and 34.4% for the nine months ended September 30, 2018 and 2017, respectively. The 2018 annual effective tax rate differed from the statutory rate of 21% primarily due to the favorable impact of the research and development credits and foreign rate differential, which were partially offset by the unfavorable impact of state income taxes, non-deductible expenses, and non-deductible equity charges. The 2017 annual effective tax rate differed from the statutory rate of 35% primarily due to the favorable impact of the research and development credits, which were partially offset by the unfavorable impact of state income taxes, foreign rate differential, and non-deductible equity charges. As of September 30, 2018 and December 31, 2017, the Company had gross unrecognized tax benefits of $10.2 million and $10.7 million, respectively. It is the Company’s policy to classify accrued interest and penalties as part of the unrecognized tax benefits, but to record the interest and penalties in operating expense. As of September 30, 2018 and December 31, 2017, the amount of accrued interest and penalties was $1.8 million and $1.4 million, respectively. The Company files income tax returns in the United States and various states and foreign jurisdictions. In the normal course of business, the Company is subject to examination by taxing authorities, including major jurisdictions such as the United States, Germany, Italy, Netherlands, and the United Kingdom. With few exceptions, as of September 30, 2018, the Company is no longer subject to U.S., state, and foreign examination for years before 2015, 2013, and 2014, respectively. Although the Company believes it has adequately provided for uncertain tax positions, the provisions on these positions may change as revised estimates are made or the underlying matters are settled or otherwise resolved. It is not possible at this time to reasonably estimate changes in the unrecognized tax benefits within the next twelve months.

Income Taxes

On December 22, 2017, the Tax Act was signed into law, most provisions of which became effective starting in 2018, including the reduction of the statutory corporate income tax rate from 35% to 21%. As of September 30, 2018, the Company has not completed the accounting for the tax effects of enactment of the Tax Act; however, in the fourth quarter of 2017, the Company made a reasonable estimate of the effects on the existing deferred tax balances and the one-time transition tax. No adjustments to the provisional amounts recorded in the fourth quarter of 2017 were made during the three and nine months ended September 30, 2018, respectively. For the nine months ended September 30, 2018, the Company assessed the effect of certain international provisions of the Tax Act that became effective January 1, 2018, and determined that these provisions had an immaterial impact; therefore, the Company did not record any impact as a result of the assessment. The Company will continue to analyze the provision for income taxes under the Tax Act as future guidance is issued. Any revisions will be treated in accordance with the measurement period guidance outlined in SEC Staff Accounting Bulletin No. 118.

The Company generally provides for income taxes in interim periods based on the estimated annual effective tax rate for the year, adjusting for discrete items in the quarter in which they arise. The annual effective tax rate before discrete items was 19.0% and 34.4% for the nine months ended September 30, 2018 and 2017, respectively.

The 2018 annual effective tax rate differed from the statutory rate of 21% primarily due to the favorable impact of the research and development credits and foreign rate differential, which were partially offset by the unfavorable impact of state income taxes, non-deductible expenses, and non-deductible equity charges. The 2017 annual effective tax rate differed from the statutory rate of 35% primarily due to the favorable impact of the research and development credits, which were partially offset by the unfavorable impact of state income taxes, foreign rate differential, and non-deductible equity charges.

As of September 30, 2018 and December 31, 2017, the Company had gross unrecognized tax benefits of $10.2 million and $10.7 million, respectively. It is the Company’s policy to classify accrued interest and penalties as part of the unrecognized tax benefits, but to record the interest and penalties in operating expense. As of September 30, 2018 and December 31, 2017, the amount of accrued interest and penalties was $1.8 million and $1.4 million, respectively.

The Company files income tax returns in the United States and various states and foreign jurisdictions. In the normal course of business, the Company is subject to examination by taxing authorities, including major jurisdictions such as the United States, Germany, Italy, Netherlands, and the United Kingdom. With few exceptions, as of September 30, 2018, the Company is no longer subject to U.S., state, and foreign examination for years before 2015, 2013, and 2014, respectively.

Although the Company believes it has adequately provided for uncertain tax positions, the provisions on these positions may change as revised estimates are made or the underlying matters are settled or otherwise resolved. It is not possible at this time to reasonably estimate changes in the unrecognized tax benefits within the next twelve months.