Debt	9 Months Ended
Debt	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt Credit Facility. On June 21, 2019, the Company amended and restated its existing $600.0 million reserve-based revolving credit facility. The initial borrowing base of the restated credit facility is $300.0 million, which was reduced from $350.0 million under the previous credit facility and is subject to semiannual redeterminations. The facility is also subject to an initial aggregate elected commitment of $270.0 million, which the Company may reduce or seek to increase in future periods in accordance with the terms of the restated credit facility. The restatement extended the credit facility maturity date to April 1, 2021 from March 31, 2020. The interest rate on outstanding borrowings was reduced from a pricing grid tied to the borrowing base utilization rate of (a) LIBOR plus an applicable margin that varies from 3.00% to 4.00% per annum, or (b) the base rate plus an applicable margin that varies from 2.00% to 3.00% per annum under the previous credit facility to a pricing grid tied to borrowing base utilization of (a) LIBOR plus an applicable margin that varies from 2.00% to 3.00% per annum, or (b) the base rate plus an applicable margin that varies from 1.00% to 2.00% per annum under the restated credit facility. Interest on base rate borrowings is payable quarterly in arrears and interest on LIBOR borrowings is payable every one, two, three or six months, at the election of the Company. Quarterly, the Company pays commitment fees assessed at annual rates of 0.50% on any available portion of the credit facility. During the three and nine-month periods ended September 30, 2019, the weighted average interest rates on the credit facility were approximately 4.5% and 5.1%, respectively. The Company has the right to prepay loans under the credit facility at any time without a prepayment penalty, other than customary “breakage” costs with respect to LIBOR loans. The restated credit facility is secured by (i) first-priority mortgages on at least 85% of the PV-9 valuation of all proved reserves included in the most recently delivered reserve report of the Company, (ii) a first-priority perfected pledge of substantially all of the capital stock owned by each credit party and equity interests in the Royalty Trusts that are owned by a credit party and (iii) a first-priority perfected security interest in substantially all the cash, cash equivalents, deposits, securities and other similar accounts, and other tangible and intangible assets of the credit parties (including but not limited to as-extracted collateral, accounts receivable, inventory, equipment, general intangibles, investment property, intellectual property, real property and the proceeds of the foregoing). Other than reducing the proportion of the Company’s proved reserves required to be subject to first-priority mortgages to 85% from 95%, these terms are materially similar to those contained in the previously existing credit facility. The restated facility includes events of default and certain customary affirmative and negative covenants which are materially similar to those under the previous credit facility. The Company must also continue to maintain certain financial covenants including (i) a maximum consolidated total net leverage ratio, measured as of the end of any fiscal quarter, of no greater than 3.50 to 1.00 and (ii) a minimum consolidated interest coverage ratio, measured as of the end of any fiscal quarter, of no less than 2.25 to 1.00. As of September 30, 2019, the Company was in compliance with all applicable covenants and had a consolidated total net leverage ratio of 0.38 and consolidated interest coverage ratio of 48.00. The Company had $62.0 million outstanding under the credit facility at September 30, 2019, and $6.0 million in outstanding letters of credit, which reduce availability under the restated credit facility on a dollar-for-dollar basis. Building Note. In February 2018, the Company fully repaid a note secured by a mortgage on the Company's downtown Oklahoma City real estate (the "Building Note") in the amount of $36.3 million, which was comprised of an initial principal amount of $35.0 million and $1.3 million in in-kind interest costs that were previously added to the principal. An unamortized premium of $1.2 million was recognized as a gain on extinguishment of debt in the unaudited condensed consolidated statement of operations for the nine-month period ended September 30, 2018 in connection with the repayment.