Income Taxes	6 Months Ended
Jun. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE R— INCOME TAXES On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act makes broad and complex changes to the U.S. tax code including, but not limited to, (1) bonus depreciation that will allow for full expensing of qualified property; (2) reduction of the U.S. federal corporate tax rate; (3) elimination of the corporate alternative minimum tax; (4) a new limitation on deductible interest expense; (5) the repeal of the domestic production activity deduction; (6) limitations on the deductibility of certain executive compensation; and (7) limitations on net operating losses generated after December 31, 2017, to 80 percent of taxable income. The SEC staff issued 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. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. As we are not subject to either the international changes of the Tax Act or other applicable provisions, we believe that the income tax effects of the Tax Act applicable to our accounting under ASC 740 is substantially complete as of June 30, 2018. Additional information that may affect the accounting under ASC 740 would include further clarification and guidance on how the Internal Revenue Service and state taxing authorities will implement the Tax Act. We did not make any Tax Act adjustments to the accounting under ASC 740 for the three and six months ended June 30, 2018, and we do not believe potential adjustments in future periods would materially impact the Company’s financial condition or results of operations. The Tax Act reduces the corporate tax rate to 21 percent, effective January 1, 2018. Because ASC 740-10-25-47 requires the effect of a change in tax laws or rates to be recognized as of the date of enactment, we were required to adjust deferred tax assets and liabilities as of December 22, 2017. Accordingly, for the year ended December 31, 2017, we recorded a decrease related to deferred tax assets and liabilities of $45.0 million and $80.8 million, respectively, with a corresponding net adjustment to deferred income tax benefit of $35.8 million. Under the Tax Act, net operating loss (NOL) deductions arising in tax years beginning after December 31, 2017 can only offset up to 80 percent of future taxable income. The Act also prohibits NOL carrybacks, but allows indefinite carryforwards for NOLs arising in tax years beginning after December 31, 2017. Net operating losses arising before January 1, 2018 are accounted for under the previous tax rules that imposed no limit on the amount of the taxable income that can be set off using NOLs and that can be carried back 2 years, and carried forward 20 years. The Tax Act repeals the corporate alternative minimum tax (AMT), effective for tax years beginning after December 31, 2017, but allows an entity to claim portions of any unused AMT credits over the next four years to offset its regular tax liability. An entity with unused AMT credits as of December 31, 2017 can first use these credits to offset its regular tax for 2017, and can then claim up to 50 percent of the remaining AMT credits in 2018, 2019, and 2020, with all remaining AMT credits refundable in 2021. For interim period reporting, we record income taxes using an estimated annual effective tax rate based upon projected annual income, forecasted permanent tax differences, discrete items and statutory rates in states in which we operate. At the end of each interim period, we update the estimated annual effective tax rate, and if the estimated tax rate changes based on new information, we make a cumulative adjustment in the period. We record the tax effect of an unusual or infrequently occurring item in the interim period in which it occurs as a discrete item of tax. For the three and six months ended June 30, 2018, we recorded a tax expense of $0.2 million and $0.7 million, respectively, related to equity compensation pursuant to ASU 2016-09. For the three and six months ended June 30, 2017, we recorded a tax benefit of $0.2 million and $1.7 million, respectively, related to equity compensation pursuant to ASU 2016-09. The effective tax rate was 14% and 17% for the three and six months ended June 30, 2018, respectively. The effective tax rate was 19% and 14% for the three and six months ended and June 30, 2017, respectively. The effective tax rate for the three and six months ended June 30, 2018 would have been 13% and 16%, respectively, without the equity compensation tax benefit or expense recorded discretely. The effective tax rate for the three and six months ended June 30, 2017 would have been 20% and 19%, respectively, without the equity compensation tax benefit or expense recorded discretely. Historically, our actual effective tax rates have differed from the statutory effective rate primarily due to the benefit received from statutory percentage depletion allowances. The deduction for statutory percentage depletion does not necessarily change proportionately to changes in income before income taxes.

NOTE R— INCOME TAXES

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act makes broad and complex changes to the U.S. tax code including, but not limited to, (1) bonus depreciation that will allow for full expensing of qualified property; (2) reduction of the U.S. federal corporate tax rate; (3) elimination of the corporate alternative minimum tax; (4) a new limitation on deductible interest expense; (5) the repeal of the domestic production activity deduction; (6) limitations on the deductibility of certain executive compensation; and (7) limitations on net operating losses generated after December 31, 2017, to 80 percent of taxable income.

The SEC staff issued 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. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. As we are not subject to either the international changes of the Tax Act or other applicable provisions, we believe that the income tax effects of the Tax Act applicable to our accounting under ASC 740 is substantially complete as of June 30, 2018. Additional information that may affect the accounting under ASC 740 would include further clarification and guidance on how the Internal Revenue Service and state taxing authorities will implement the Tax Act. We did not make any Tax Act adjustments to the accounting under ASC 740 for the three and six months ended June 30, 2018, and we do not believe potential adjustments in future periods would materially impact the Company’s financial condition or results of operations.

The Tax Act reduces the corporate tax rate to 21 percent, effective January 1, 2018. Because ASC 740-10-25-47 requires the effect of a change in tax laws or rates to be recognized as of the date of enactment, we were required to adjust deferred tax assets and liabilities as of December 22, 2017. Accordingly, for the year ended December 31, 2017, we recorded a decrease related to deferred tax assets and liabilities of $45.0 million and $80.8 million, respectively, with a corresponding net adjustment to deferred income tax benefit of $35.8 million.

Under the Tax Act, net operating loss (NOL) deductions arising in tax years beginning after December 31, 2017 can only offset up to 80 percent of future taxable income. The Act also prohibits NOL carrybacks, but allows indefinite carryforwards for NOLs arising in tax years beginning after December 31, 2017. Net operating losses arising before January 1, 2018 are accounted for under the previous tax rules that imposed no limit on the amount of the taxable income that can be set off using NOLs and that can be carried back 2 years, and carried forward 20 years.

The Tax Act repeals the corporate alternative minimum tax (AMT), effective for tax years beginning after December 31, 2017, but allows an entity to claim portions of any unused AMT credits over the next four years to offset its regular tax liability. An entity with unused AMT credits as of December 31, 2017 can first use these credits to offset its regular tax for 2017, and can then claim up to 50 percent of the remaining AMT credits in 2018, 2019, and 2020, with all remaining AMT credits refundable in 2021.

For interim period reporting, we record income taxes using an estimated annual effective tax rate based upon projected annual income, forecasted permanent tax differences, discrete items and statutory rates in states in which we operate. At the end of each interim period, we update the estimated annual effective tax rate, and if the estimated tax rate changes based on new information, we make a cumulative adjustment in the period. We record the tax effect of an unusual or infrequently occurring item in the interim period in which it occurs as a discrete item of tax.

For the three and six months ended June 30, 2018, we recorded a tax expense of $0.2 million and $0.7 million, respectively, related to equity compensation pursuant to ASU 2016-09. For the three and six months ended June 30, 2017, we recorded a tax benefit of $0.2 million and $1.7 million, respectively, related to equity compensation pursuant to ASU 2016-09.

The effective tax rate was 14% and 17% for the three and six months ended June 30, 2018, respectively. The effective tax rate was 19% and 14% for the three and six months ended and June 30, 2017, respectively. The effective tax rate for the three and six months ended June 30, 2018 would have been 13% and 16%, respectively, without the equity compensation tax benefit or expense recorded discretely. The effective tax rate for the three and six months ended June 30, 2017 would have been 20% and 19%, respectively, without the equity compensation tax benefit or expense recorded discretely.

Historically, our actual effective tax rates have differed from the statutory effective rate primarily due to the benefit received from statutory percentage depletion allowances. The deduction for statutory percentage depletion does not necessarily change proportionately to changes in income before income taxes.