Emergence from Voluntary Reorganization under Chapter 11	12 Months Ended
	Dec. 31, 2020
Reorganizations [Abstract]
Emergence from Voluntary Reorganization under Chapter 11	Emergence from Voluntary Reorganization under Chapter 11 Due to the volatile market environment that drove a severe downturn in crude oil and natural gas prices in early 2020, as well as the unprecedented impact of the novel coronavirus 2019 (“COVID-19”) pandemic, the Company evaluated strategic alternatives to reduce its debt, increase financial flexibility and position the Company for long-term success. On September 30, 2020 (the “Petition Date”), Oasis Petroleum Inc. and its affiliates Oasis Petroleum LLC (“OP LLC”), OPNA, Oasis Well Services LLC (“OWS”), Oasis Petroleum Marketing LLC, OP Permian, OMS Holdings LLC, Oasis Midstream Services (“OMS”) and OMP GP LLC (“OMP GP”) (collectively, the “Debtors”) filed voluntary petitions (the “Chapter 11 Cases”) for relief under chapter 11 of title 11 (“Chapter 11”) of the United States Code (the “Bankruptcy Code”) in the United States Bankruptcy Court for the Southern District of Texas (the “Bankruptcy Court”). On November 10, 2020, the Bankruptcy Court confirmed the Joint Prepackaged Chapter 11 Plan of Reorganization of Oasis Petroleum Inc. and its Debtor Affiliates (the “Plan”), and on November 19, 2020 (the “Emergence Date”), the Debtors implemented the Plan and emerged from the Chapter 11 Cases. OMP and its subsidiaries, OMP Operating LLC (“OMP Operating”), Bobcat DevCo LLC (“Bobcat DevCo”), Beartooth DevCo LLC (“Beartooth DevCo”), Bighorn DevCo LLC (“Bighorn DevCo”) and Panther DevCo LLC (“Panther DevCo”), were not included in the Chapter 11 Cases. At the Emergence Date, the Company adopted fresh start accounting in accordance with Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification 852, Reorganizations (“ASC 852”), which resulted in a new basis of accounting and the Company becoming a new entity for financial reporting purposes (see Note 3—Fresh Start Accounting). As a result of the adoption of fresh start accounting and the effects of the implementation of the Plan, the consolidated financial statements after the Emergence Date are not comparable to the consolidated financial statements prior to that date. References to “Successor” relate to the reorganized Company’s financial position and results of operations as of and subsequent to the Emergence Date. References to “Predecessor” relate to the Company’s financial position prior to, and results of operations through and including, the Emergence Date. Although the Company is no longer a debtor-in-possession, the Predecessor operated as a debtor-in-possession from the Petition Date through the Emergence Date. As such, certain aspects of the Chapter 11 Cases and related matters are described below in order to provide context to the Company’s financial condition and results of operations for the period presented. In accordance with the Plan, the following significant transactions occurred on the Emergence Date: •Shares of the Predecessor’s common stock outstanding immediately prior to the Emergence Date were cancelled, and on the Emergence Date, the Company issued (i) 20,000,000 shares of the Successor’s common stock pro rata to holders of the Predecessor’s Notes (as defined below) and (ii) 1,621,622 warrants (the “Warrants”) pro rata to holders of the Predecessor’s common stock. The Warrants are exercisable to purchase one share of the Successor’s common stock per Warrant at an initial exercise price of $94.57 and expire on November 19, 2024. •All outstanding obligations under the following notes (collectively, the “Notes”) issued by the Predecessor were cancelled: (i) 6.50% senior unsecured notes due 2021; (ii) 6.875% senior unsecured notes due 2022; (iii) 6.875% senior unsecured notes due 2023; (iv) 6.250% senior unsecured notes due 2026; and (v) 2.625% senior unsecured convertible notes due 2023. •Oasis Petroleum Inc., as parent, OPNA, as borrower, and Wells Fargo Bank, N.A. (“Wells Fargo”), as administrative agent, issuing bank and swingline lender, and the lenders party thereto entered into a reserves-based credit agreement (the “Oasis Credit Facility”) with maximum aggregate commitments in the amount of $1,500.0 million and an initial borrowing base of $575.0 million. •The Amended and Restated Credit Agreement, dated as of October 16, 2018 (as amended prior to the Emergence Date, the “Predecessor Credit Facility”), by and among the Predecessor, as borrower, the lenders party thereto, and Wells Fargo, as administrative agent, was terminated and holders of claims under the Predecessor Credit Facility had such obligations refinanced through the Oasis Credit Facility. Notwithstanding the foregoing, the Specified Default Interest (as defined in Note 15—Long-Term Debt) related to the Predecessor Credit Facility was discharged, released and deemed waived by the lenders. •The Senior Secured Superpriority Debtor-in-Possession Credit Agreement, dated as of October 2, 2020 (the “DIP Credit Facility”), by and among the Predecessor, as borrower, its subsidiaries party thereto, as guarantors, the lenders party thereto, and Wells Fargo, as administrative agent, was terminated and the holders of claims under the DIP Credit Facility had such obligations refinanced through the Oasis Credit Facility. •Mirada Claims (as defined in the Plan) were treated in accordance with the Settlement and Mutual Release Agreement dated September 28, 2020 (the “Mirada Settlement Agreement”) with Mirada Energy, LLC and certain related parties. •The holders of other secured claims, other priority claims and general unsecured claims received payment in full in cash upon emergence or through the ordinary course of business after the Emergence Date. •The Company adopted the Oasis Petroleum Inc. 2020 Long Term Incentive Plan (the “2020 LTIP”) effective on the Emergence Date and reserved 2,402,402 shares of its Successor’s common stock for distribution under the 2020 LTIP. No shares were issued under the 2020 LTIP as of the Emergence Date. In addition, on the Emergence Date, the conditions were satisfied for the waiver, discharge and forgiveness of the OMP Specified Default Interest (as defined in Note 15—Long-Term Debt) under the revolving credit facility among OMP, as parent, OMP Operating, as borrower, Wells Fargo, as administrative agent, and the lenders party thereto (the “OMP Credit Facility”), and payment of the OMP Specified Default Interest was permanently waived by the lenders party to the OMP Credit Facility. As of the Emergence Date, by operation of and in accordance with the Plan, the Board of Directors consisted of seven members, comprised of the Company’s Chief Executive Officer, Thomas B. Nusz, and six new members, Douglas E. Brooks, Samantha Holroyd, John Jacobi, Robert McNally, Cynthia L. Walker and John Lancaster. Subsequently, on December 22, 2020, Thomas B. Nusz retired as Chief Executive Officer and as a director of Oasis Petroleum Inc. In order to eliminate the Board vacancy created by Mr. Nusz’s departure, the size of the Board of Directors was reduced from seven to six. The Board of Directors appointed Douglas E. Brooks to serve as Chief Executive Officer, in addition to his role as Board Chair, during the period that it conducts a search for a new Chief Executive Officer. Executory Contracts Subject to certain exceptions, under the Bankruptcy Code, the Debtors were entitled to assume, assign or reject certain executory contracts and unexpired leases subject to the approval of the Bankruptcy Court and certain other conditions. The Debtors did not reject any executory contracts and, under the terms of the Plan, all executory contracts or unexpired leases not otherwise assumed or rejected were deemed assumed by the applicable Debtor. Liabilities Subject to Compromise During bankruptcy, the Debtors’ liabilities were segregated into those subject to compromise and those not subject to compromise under ASC 852. Liabilities subject to compromise represent pre-petition obligations that were not fully secured and that had at least a possibility of not being repaid at the full claim amount. The Predecessor presented liabilities subject to compromise at the expected amount of allowed claims and aggregated as a single line item on its balance sheet. See Note 3—Fresh Start Accounting for further details on the settlement of liabilities subject to compromise in accordance with the Plan. As of the Petition Date, the Company reclassified its Notes to liabilities subject to compromise and discontinued recording interest on its Notes. The contractual interest expense on the Notes not accrued in the Company’s Consolidated Statements of Operations was $15.6 million for the period from the Petition Date through the Emergence Date.