Income Taxes	9 Months Ended
Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rate for the three and nine months ended September 30, 2016 was 33.0% and 34.0%, respectively. The Company’s effective tax rate for the three and nine months ended September 30, 2015 was 43.0% and 28.7%, respectively. The effective tax rates for the three and nine months ended September 30, 2016 and the nine months ended September 30, 2015 were lower than the combined federal statutory rate and the statutory rates for the states in which the Company conducts business due to the impact of permanent differences on pre-tax loss for these periods, while the effective tax rate for three months ended September 30, 2015 was higher than the combined federal statutory rate and the statutory rates for the states in which the Company conducts business due to the impact of permanent differences on pre-tax income for the period. The permanent differences were primarily between amounts expensed for book purposes versus the amounts deductible for income tax purposes related to stock-based compensation vesting during the three and nine months ended September 30, 2016 and 2015. While the Company is in an overall deferred tax liability position, the Company had deferred tax assets for its federal and state tax net operating losses and other tax carryforwards recorded in deferred income taxes at September 30, 2016. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. During the nine months ended September 30, 2016, the Company recorded a valuation allowance of $0.8 million and $0.6 million for Montana net operating losses and for federal charitable contribution carryovers, respectively, based on management’s assessment that it is more likely than not that these net deferred tax assets will not be realized prior to their expiration due to their short carryover periods, current economic conditions and expectations for the future. Management determined that a valuation allowance was not required for its U.S. federal tax net operating loss carryforwards as they are expected to be fully utilized before their expiration. However, the amount of deferred tax assets considered realizable could be reduced in the future if subjective positive evidence becomes limited by objective negative evidence. Management’s estimates of future taxable income are significantly affected by changes in commodity prices, the timing and amount of future production and future operating and capital costs. At September 30, 2016, the Company did not have any uncertain tax positions requiring adjustments to its tax liability.

Income Taxes

The Company’s effective tax rate for the three and nine months ended September 30, 2016 was 33.0% and 34.0%, respectively. The Company’s effective tax rate for the three and nine months ended September 30, 2015 was 43.0% and 28.7%, respectively. The effective tax rates for the three and nine months ended September 30, 2016 and the nine months ended September 30, 2015 were lower than the combined federal statutory rate and the statutory rates for the states in which the Company conducts business due to the impact of permanent differences on pre-tax loss for these periods, while the effective tax rate for three months ended September 30, 2015 was higher than the combined federal statutory rate and the statutory rates for the states in which the Company conducts business due to the impact of permanent differences on pre-tax income for the period. The permanent differences were primarily between amounts expensed for book purposes versus the amounts deductible for income tax purposes related to stock-based compensation vesting during the three and nine months ended September 30, 2016 and 2015.

While the Company is in an overall deferred tax liability position, the Company had deferred tax assets for its federal and state tax net operating losses and other tax carryforwards recorded in deferred income taxes at September 30, 2016. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. During the nine months ended September 30, 2016, the Company recorded a valuation allowance of $0.8 million and $0.6 million for Montana net operating losses and for federal charitable contribution carryovers, respectively, based on management’s assessment that it is more likely than not that these net deferred tax assets will not be realized prior to their expiration due to their short carryover periods, current economic conditions and expectations for the future. Management determined that a valuation allowance was not required for its U.S. federal tax net operating loss carryforwards as they are expected to be fully utilized before their expiration. However, the amount of deferred tax assets considered realizable could be reduced in the future if subjective positive evidence becomes limited by objective negative evidence. Management’s estimates of future taxable income are significantly affected by changes in commodity prices, the timing and amount of future production and future operating and capital costs.

At September 30, 2016, the Company did not have any uncertain tax positions requiring adjustments to its tax liability.