Income taxes	9 Months Ended
Sep. 30, 2018
Income taxes [Abstract]
Income taxes	6. Income taxes We recorded an income tax provision for the third quarter of 2018 of $581 thousand at an effective tax rate of 18.4%, compared to an income tax provision during the third quarter of 2017 of $769 thousand at an effective tax rate of 29.8%. For the nine months ended September 30, 2018, we recorded an income tax provision of $1.06 million at an effective tax rate of 19.2%, compared to an income tax provision during the nine months ended September 30, 2017 of $1.66 million at an effective tax rate of 31.4%. We expect our annual effective tax rate for 2018 to be between 19% and 20%. The effective tax rate for the three and nine months ended September 30, 2018 was lower than the effective tax rate for the three and nine months ended September 30, 2017 due to the passage of the Tax Cuts and Jobs Act (the "Tax Reform Act") enacted on December 22, 2017. The legislation significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a one-time repatriation tax on undistributed foreign earnings. The Tax Reform Act reduced the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate effective January 1, 2018 and, as a result, reduced our statutory U.S. corporate income tax rate from 34% to 21%. On December 22, 2017, the Securities and Exchange Commission ("SEC") staff issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations where a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. SAB 118 provides a measurement period, not to exceed one year from the enactment of the Tax Reform Act. In accordance with SAB 118, the Company has recognized provisional tax impacts related to the revaluation of deferred tax assets and liabilities and included these amounts in its consolidated financial statements for the year ended December 31, 2017, and no changes were made to these provisional amounts during the quarter ended September 30, 2018. The ultimate impact may differ from these provisional amounts, possibly materially, due to, among other things, additional analysis, changes in interpretations and assumptions, additional regulatory guidance from Treasury, the Internal Revenue Service and State Governments, and actions the Company may take as a result of the Tax Reform Act, but the enactment of this legislation did not result in a material adjustment for the nine months ended September 30, 2018. While the Tax Reform Act provides for a territorial tax system, beginning in 2018, it includes two new U.S. tax base erosion provisions, the global intangible low-taxed income ("GILTI") provisions and the base-erosion and anti-abuse tax ("BEAT") provisions. The GILTI provisions require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary's tangible assets. The BEAT provisions in the Tax Reform Act eliminate the deduction of certain base-erosion payments made to related foreign corporations, and impose a minimum tax if greater than regular income tax. The Company has not recorded any impacts of GILTI or BEAT in its consolidated financial statements for the quarter ended September 30, 2018. We are subject to U.S. federal income tax, as well as income tax in certain state and foreign jurisdictions. We have substantially concluded all U.S. federal income tax, state and local, and foreign tax regulatory examination matters through 2014. However, our federal tax returns for the years 2015 through 2017 remain open to examination. Various state and foreign tax jurisdiction tax years remain open to examination as well, though we believe that any additional assessment would be immaterial to the Condensed Consolidated Financial Statements. As of September 30, 2018, we had $76 thousand of total gross unrecognized tax benefits that, if recognized, would favorably affect the effective income tax rate in any future periods. During the third quarter of 2018, we recognized $28 thousand of previously unrecognized tax benefits as the statute of limitations on the use of our 2014 R&D credits expired during the third quarter of 2018. We recognize interest and penalties related to uncertain tax positions in the income tax provision reported as "Deferred tax assets" in the Condensed Consolidated Balance Sheet. As of September 30, 2018, we have $14 thousand of accrued interest and penalties related to uncertain tax positions. The Company maintains a valuation allowance against certain deferred tax assets where realization is not certain.

6. Income taxes

We recorded an income tax provision for the third quarter of 2018 of $581 thousand at an effective tax rate of 18.4%, compared to an income tax provision during the third quarter of 2017 of $769 thousand at an effective tax rate of 29.8%. For the nine months ended September 30, 2018, we recorded an income tax provision of $1.06 million at an effective tax rate of 19.2%, compared to an income tax provision during the nine months ended September 30, 2017 of $1.66 million at an effective tax rate of 31.4%. We expect our annual effective tax rate for 2018 to be between 19% and 20%. The effective tax rate for the three and nine months ended September 30, 2018 was lower than the effective tax rate for the three and nine months ended September 30, 2017 due to the passage of the Tax Cuts and Jobs Act (the "Tax Reform Act") enacted on December 22, 2017. The legislation significantly changes U.S. tax law by, among other things, lowering corporate income tax rates, implementing a territorial tax system and imposing a one-time repatriation tax on undistributed foreign earnings. The Tax Reform Act reduced the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate effective January 1, 2018 and, as a result, reduced our statutory U.S. corporate income tax rate from 34% to 21%.

On December 22, 2017, the Securities and Exchange Commission ("SEC") staff issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations where a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. SAB 118 provides a measurement period, not to exceed one year from the enactment of the Tax Reform Act. In accordance with SAB 118, the Company has recognized provisional tax impacts related to the revaluation of deferred tax assets and liabilities and included these amounts in its consolidated financial statements for the year ended December 31, 2017, and no changes were made to these provisional amounts during the quarter ended September 30, 2018. The ultimate impact may differ from these provisional amounts, possibly materially, due to, among other things, additional analysis, changes in interpretations and assumptions, additional regulatory guidance from Treasury, the Internal Revenue Service and State Governments, and actions the Company may take as a result of the Tax Reform Act, but the enactment of this legislation did not result in a material adjustment for the nine months ended September 30, 2018.

While the Tax Reform Act provides for a territorial tax system, beginning in 2018, it includes two new U.S. tax base erosion provisions, the global intangible low-taxed income ("GILTI") provisions and the base-erosion and anti-abuse tax ("BEAT") provisions. The GILTI provisions require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary's tangible assets. The BEAT provisions in the Tax Reform Act eliminate the deduction of certain base-erosion payments made to related foreign corporations, and impose a minimum tax if greater than regular income tax. The Company has not recorded any impacts of GILTI or BEAT in its consolidated financial statements for the quarter ended September 30, 2018.

We are subject to U.S. federal income tax, as well as income tax in certain state and foreign jurisdictions. We have substantially concluded all U.S. federal income tax, state and local, and foreign tax regulatory examination matters through 2014. However, our federal tax returns for the years 2015 through 2017 remain open to examination. Various state and foreign tax jurisdiction tax years remain open to examination as well, though we believe that any additional assessment would be immaterial to the Condensed Consolidated Financial Statements.

As of September 30, 2018, we had $76 thousand of total gross unrecognized tax benefits that, if recognized, would favorably affect the effective income tax rate in any future periods. During the third quarter of 2018, we recognized $28 thousand of previously unrecognized tax benefits as the statute of limitations on the use of our 2014 R&D credits expired during the third quarter of 2018.

We recognize interest and penalties related to uncertain tax positions in the income tax provision reported as "Deferred tax assets" in the Condensed Consolidated Balance Sheet. As of September 30, 2018, we have $14 thousand of accrued interest and penalties related to uncertain tax positions. The Company maintains a valuation allowance against certain deferred tax assets where realization is not certain.