Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the U.S. government enacted tax reform legislation commonly known as the Tax Cuts and Jobs Act (the “Tax Act”), resulting in significant modifications to U.S. tax law. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. As of September 30, 2018, the Company has not made a measurement period adjustment and the accounting for the Tax Act remains incomplete. The Company's tax provision for interim periods is determined using an estimated annual effective tax rate, adjusted for discrete items arising in that quarter. In each quarter, the estimated annual effective tax rate is updated and a year-to-date adjustment is made to the provision. The Company's quarterly effective tax rate is subject to significant volatility due to the effect of discrete items arising in a given quarter. Income tax expense for the quarter and year to date ended September 30, 2018 was $2,673 and $7,244, respectively, for an effective tax rate for the quarter of 22.9 percent and for the year to date of 22.1 percent. For the quarter, the effective tax rate differed from the 21 percent federal statutory rate (as lowered by the Tax Act) on pretax income, primarily due to state taxes, including a reduction of state taxes for state income tax credits in Indiana and Kansas. Year to date, the effective tax rate differed from the 21 percent federal statutory rate (as lowered by the Tax Act) on pretax income, primarily due to state taxes, including a reduction of state taxes for state income tax credits in Indiana and Kansas, a change in estimate related to the sale of the Company's interest in ICP, and an increase in the Company’s valuation allowance related to capital loss carryforwards and state net operating losses. These amounts were partially offset by the impact of income tax benefits related to share-based compensation as accounted for in ASU 2016-09, Compensation - Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting. Income tax expense for the quarter and year to date ended September 30, 2017 was $7,491 and $13,292, respectively, for an effective tax rate for the quarter of 34.6 percent and for the year to date of 31.3 percent. The increase in tax expense, compared to prior quarters in 2017, largely relates to the Company’s sale of its interest in ICP, and the corresponding tax gain recognized in the annual effective tax rate calculation. The effective tax rate differed from the 35 percent federal statutory rate on pretax income, primarily due to the impact of income tax benefits related to share-based compensation as accounted for in ASU 2016-09, Compensation - Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting, the domestic production activities deduction, state tax planning including state income tax credits in Indiana and Kansas, and changes to the Company's valuation allowance, partially offset by state taxes.

Income Taxes

On December 22, 2017, the U.S. government enacted tax reform legislation commonly known as the Tax Cuts and Jobs Act (the “Tax Act”), resulting in significant modifications to U.S. tax law. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. As of September 30, 2018, the Company has not made a measurement period adjustment and the accounting for the Tax Act remains incomplete.

The Company's tax provision for interim periods is determined using an estimated annual effective tax rate, adjusted for discrete items arising in that quarter. In each quarter, the estimated annual effective tax rate is updated and a year-to-date adjustment is made to the provision. The Company's quarterly effective tax rate is subject to significant volatility due to the effect of discrete items arising in a given quarter. Income tax expense for the quarter and year to date ended September 30, 2018 was $2,673 and $7,244, respectively, for an effective tax rate for the quarter of 22.9 percent and for the year to date of 22.1 percent. For the quarter, the effective tax rate differed from the 21 percent federal statutory rate (as lowered by the Tax Act) on pretax income, primarily due to state taxes, including a reduction of state taxes for state income tax credits in Indiana and Kansas. Year to date, the effective tax rate differed from the 21 percent federal statutory rate (as lowered by the Tax Act) on pretax income, primarily due to state taxes, including a reduction of state taxes for state income tax credits in Indiana and Kansas, a change in estimate related to the sale of the Company's interest in ICP, and an increase in the Company’s valuation allowance related to capital loss carryforwards and state net operating losses. These amounts were partially offset by the impact of income tax benefits related to share-based compensation as accounted for in ASU 2016-09, Compensation - Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting.

Income tax expense for the quarter and year to date ended September 30, 2017 was $7,491 and $13,292, respectively, for an effective tax rate for the quarter of 34.6 percent and for the year to date of 31.3 percent. The increase in tax expense, compared to prior quarters in 2017, largely relates to the Company’s sale of its interest in ICP, and the corresponding tax gain recognized in the annual effective tax rate calculation. The effective tax rate differed from the 35 percent federal statutory rate on pretax income, primarily due to the impact of income tax benefits related to share-based compensation as accounted for in ASU 2016-09, Compensation - Stock Compensation (Topic 718) Improvements to Employee Share-Based Payment Accounting, the domestic production activities deduction, state tax planning including state income tax credits in Indiana and Kansas, and changes to the Company's valuation allowance, partially offset by state taxes.