Income taxes	9 Months Ended
Sep. 30, 2018
Income taxes [Abstract]
Income taxes	9. Income taxes The estimated effective annual tax rate for the Company, which excludes discrete adjustments, was 26% and 32% for the nine months ended September 30, 2018 and 2017, respectively. The decrease in the estimated effective annual tax rate is primarily due to the impact of the Tax Reform Act enacted on December 22, 2017, which reduced the U.S. federal corporate income tax rate from 35% to 21%, offset by state taxes, non-deductible expenses, international provisions from the U.S. tax reform and the impact of a change in the Company's jurisdictional mix of earnings. For the nine months ended September 30, 2018 and 2017, the Company recorded a discrete tax benefit of $8.7 million and $3.3 million, respectively, primarily associated with equity awards activity and finalizing positions taken on the Company's 2017 US federal and state income tax filings. On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. For the nine months ended September 30, 2018, the Company revised certain provisional estimates recognized in 2017 upon the filing of US federal and state income tax filings. As the Internal Revenue Service and state jurisdictions continue to issue and/or clarify guidance, additional work may be necessary for a more detailed analysis of the Company's deferred tax assets and liabilities, its historical foreign earnings, as well as potential correlative adjustments. Any correlative adjustment to these amounts will be recorded to current tax expense in the final quarter of 2018 when the analysis is complete.

9. Income taxes

The estimated effective annual tax rate for the Company, which excludes discrete adjustments, was 26% and 32% for the nine months ended September 30, 2018 and 2017, respectively. The decrease in the estimated effective annual tax rate is primarily due to the impact of the Tax Reform Act enacted on December 22, 2017, which reduced the U.S. federal corporate income tax rate from 35% to 21%, offset by state taxes, non-deductible expenses, international provisions from the U.S. tax reform and the impact of a change in the Company's jurisdictional mix of earnings. For the nine months ended September 30, 2018 and 2017, the Company recorded a discrete tax benefit of $8.7 million and $3.3 million, respectively, primarily associated with equity awards activity and finalizing positions taken on the Company's 2017 US federal and state income tax filings.

On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. For the nine months ended September 30, 2018, the Company revised certain provisional estimates recognized in 2017 upon the filing of US federal and state income tax filings. As the Internal Revenue Service and state jurisdictions continue to issue and/or clarify guidance, additional work may be necessary for a more detailed analysis of the Company's deferred tax assets and liabilities, its historical foreign earnings, as well as potential correlative adjustments. Any correlative adjustment to these amounts will be recorded to current tax expense in the final quarter of 2018 when the analysis is complete.