Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income taxes	Income taxes The total amount of unrecognized tax benefits that, if recognized, would impact the effective tax rate was approximately $9.7 million as of September 30, 2018, and $10.7 million as of December 31, 2017. The amount of accrued interest and penalties payable related to unrecognized tax benefits was $1.4 million as of September 30, 2018, and $1.6 million as of December 31, 2017. It is reasonably possible that the amount of unrecognized benefits with respect to certain of our unrecognized tax positions will increase or decrease within the next 12 months. These changes may be the result of settlement of ongoing audits, lapses of statutes of limitations or other regulatory developments. At this time, we estimate the amount of gross unrecognized tax positions may be reduced by up to approximately $3.9 million within the next 12 months primarily due to lapses of statutes of limitations and settlement of ongoing audits in various jurisdictions. As discussed in Note 1, the Tax Act, was enacted into law as of December 22, 2017. Among other provisions, the Tax Act reduced the federal tax rate to 21% effective for us as of January 1, 2018. On the same date, 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 Act. We recognized the provisional tax impacts related to the revaluation of deferred tax assets and liabilities and included these amounts in our consolidated financial statements for the year ended December 31, 2017. We completed our 2017 U.S. federal return during the third quarter of 2018 and recorded measurement period adjustments for the revaluation of deferred tax assets and liabilities at the reduced 21% federal tax rate that reduced tax expense by $5.3 million and our third quarter effective income tax rate by five percentage points. We will continue to analyze the effects of the Tax Act on our consolidated financial statements when state corporate income tax returns are filed in late 2018. Any additional impacts from the enactment will be recorded as they are identified during the measurement period as provided for in Staff Accounting Bulletin No. 118.

Income taxes

The total amount of unrecognized tax benefits that, if recognized, would impact the effective tax rate was approximately $9.7 million as of September 30, 2018, and $10.7 million as of December 31, 2017. The amount of accrued interest and penalties payable related to unrecognized tax benefits was $1.4 million as of September 30, 2018, and $1.6 million as of December 31, 2017.

It is reasonably possible that the amount of unrecognized benefits with respect to certain of our unrecognized tax positions will increase or decrease within the next 12 months. These changes may be the result of settlement of ongoing audits, lapses of statutes of limitations or other regulatory developments. At this time, we estimate the amount of gross unrecognized tax positions may be reduced by up to approximately $3.9 million within the next 12 months primarily due to lapses of statutes of limitations and settlement of ongoing audits in various jurisdictions.

As discussed in Note 1, the Tax Act, was enacted into law as of December 22, 2017. Among other provisions, the Tax Act reduced the federal tax rate to 21% effective for us as of January 1, 2018. On the same date, 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 Act. We recognized the provisional tax impacts related to the revaluation of deferred tax assets and liabilities and included these amounts in our consolidated financial statements for the year ended December 31, 2017. We completed our 2017 U.S. federal return during the third quarter of 2018 and recorded measurement period adjustments for the revaluation of deferred tax assets and liabilities at the reduced 21% federal tax rate that reduced tax expense by $5.3 million and our third quarter effective income tax rate by five percentage points. We will continue to analyze the effects of the Tax Act on our consolidated financial statements when state corporate income tax returns are filed in late 2018. Any additional impacts from the enactment will be recorded as they are identified during the measurement period as provided for in Staff Accounting Bulletin No. 118.