Gulfport Energy (GPOR) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Entity Registrant Name	GULFPORT ENERGY CORP
Entity Central Index Key	874,499
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2,018
Entity Filer Category	Large Accelerated Filer
Document Fiscal Period Focus	Q1
Entity Common Stock, Shares Outstanding (in shares)		173,657,895

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 118,613	$ 99,557
Accounts receivable—oil and natural gas	199,457	182,213
Prepaid expenses and other current assets	7,564	4,912
Short-term derivative instruments	50,906	78,847
Total current assets	376,540	365,529
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,971,119 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	9,470,697	9,169,156
Other property and equipment	89,648	86,754
Accumulated depletion, depreciation, amortization and impairment	(4,264,647)	(4,153,733)
Property and equipment, net	5,295,698	5,102,177
Other assets:
Equity investments	311,694	302,112
Long-term derivative instruments	15,769	8,685
Deferred tax asset	0	1,208
Inventories	8,505	8,227
Other assets	20,186	19,814
Total other assets	356,154	340,046
Total assets	6,028,392	5,807,752
Current liabilities:
Accounts payable and accrued liabilities	577,548	553,609
Asset retirement obligation—current	120	120
Short-term derivative instruments	37,570	32,534
Current maturities of long-term debt	629	622
Total current liabilities	615,867	586,885
Long-term derivative instruments	2,499	2,989
Asset retirement obligation—long-term	76,267	74,980
Deferred tax liability	2,884	0
Other non-current liabilities	2,963	2,963
Long-term debt, net of current maturities	2,239,023	2,038,321
Total liabilities	2,939,503	2,706,138
Commitments and contingencies (Note 9)
Preferred stock, $.01 par value; 5,000,000 authorized, 30,000 authorized as redeemable 12% cumulative preferred stock, Series A; 0 issued and outstanding	0	0
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,523,487 issued and outstanding at March 31, 2018 and 183,105,910 at December 31, 2017	1,735	1,831
Paid-in capital	4,319,034	4,416,250
Accumulated other comprehensive loss	(46,042)	(40,539)
Retained deficit	(1,185,838)	(1,275,928)
Total stockholders’ equity	3,088,889	3,101,614
Total liabilities and stockholders’ equity	$ 6,028,392	$ 5,807,752

Consolidated Balance Sheets (U3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Capitalized costs of oil and natural gas properties excluded from amortization	$ 2,971,119	$ 2,912,974
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock dividend rate, percent	12.00%	12.00%
Redeemable preferred stock, shares authorized (in shares)	30,000	30,000
Preferred stock Series A, issued (in shares)	0	0
Preferred stock Series A, outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares, issued (in shares)	173,523,487	183,105,910
Common stock, shares, outstanding (in shares)	173,523,487	183,105,910

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Natural gas sales	$ 249,399	$ 177,837
Oil and condensate sales	45,686	24,411
Natural gas liquid sales	46,836	31,179
Net (loss) gain on natural gas, oil, and NGL derivatives	(16,529)	99,577
Total revenues	325,392	333,004
Costs and expenses:
Lease operating expenses	18,906	19,303
Production taxes	6,854	3,906
Midstream gathering and processing	64,193	47,941
Depreciation, depletion and amortization	111,018	65,991
General and administrative	13,099	12,600
Accretion expense	1,004	282
Acquisition expense	0	1,298
Total costs and expenses	215,074	151,321
INCOME (LOSS) FROM OPERATIONS	110,318	181,683
OTHER (INCOME) EXPENSE:
Interest expense	33,965	23,479
Interest income	(37)	(842)
(Income) loss from equity method investments, net	(13,536)	4,907
Other (income) expense	(95)	(316)
Total other (income) expense	20,297	27,228
INCOME (LOSS) BEFORE INCOME TAXES	90,021	154,455
INCOME TAX BENEFIT	(69)	0
NET INCOME (LOSS)	$ 90,090	$ 154,455
NET INCOME PER COMMON SHARE:
Basic (in usd per share)	$ 0.50	$ 0.91
Diluted (in usd per share)	$ 0.50	$ 0.91
Weighted average common shares outstanding - Basic (in shares)	180,714,881	170,272,685
Weighted average common shares outstanding - Diluted (in shares)	180,802,301	170,488,519

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 90,090	$ 154,455
Foreign currency translation adjustment	(5,503)	1,373
Other comprehensive (loss) income	(5,503)	1,373
Comprehensive income	$ 84,587	$ 155,828

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Accumulated Other Comprehensive Income (loss)	Retained Deficit
Beginning Balance (in shares) at Dec. 31, 2016		158,829,816
Beginning Balance at Dec. 31, 2016	$ 2,183,892	$ 1,588	$ 3,946,442	$ (53,058)	$ (1,711,080)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	154,455				154,455
Other Comprehensive Income	1,373			1,373
Stock-based Compensation	2,553		2,553
Issuance of Common Stock for the Vitruvian Acquisition, net of related expenses (in shares)		23,852,117
Issuance of Common Stock for the Vitruvian Acquisition, net of related expenses	459,481	$ 239	459,242
Issuance of Restricted Stock (in shares)		153,868
Issuance of Restricted Stock	0	$ 1	(1)
Ending Balance (in shares) at Mar. 31, 2017		182,835,801
Ending Balance at Mar. 31, 2017	$ 2,801,754	$ 1,828	4,408,236	(51,685)	(1,556,625)
Beginning Balance (in shares) at Dec. 31, 2017	183,105,910	183,105,910
Beginning Balance at Dec. 31, 2017	$ 3,101,614	$ 1,831	4,416,250	(40,539)	(1,275,928)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	90,090				90,090
Other Comprehensive Income	(5,503)			(5,503)
Stock-based Compensation	2,685		2,685
Shares Repurchased (in shares)		(9,692,356)
Shares Repurchased	(99,997)	$ (97)	(99,900)
Issuance of Restricted Stock (in shares)		109,933
Issuance of Restricted Stock	$ 0	$ 1	(1)
Ending Balance (in shares) at Mar. 31, 2018	173,523,487	173,523,487
Ending Balance at Mar. 31, 2018	$ 3,088,889	$ 1,735	$ 4,319,034	$ (46,042)	$ (1,185,838)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 90,090	$ 154,455
Adjustments to reconcile net income to net cash provided by operating activities:
Accretion	1,004	282
Depletion, depreciation and amortization	111,018	65,991
Stock-based compensation expense	1,611	1,532
(Gain) loss from equity investments	(13,495)	5,150
Change in fair value of derivative instruments	25,403	(106,796)
Deferred income tax benefit	(69)	0
Amortization of loan commitment fees	1,488	1,088
Changes in operating assets and liabilities:
Increase in accounts receivable	(15,450)	(21,393)
Increase in accounts receivable—related party		(23)
Increase in prepaid expenses and other current assets	(2,652)	(8,366)
Decrease (increase) in other assets	14	(4,013)
Increase in accounts payable, accrued liabilities and other	27,486	54,738
Settlement of asset retirement obligation	(99)
Net cash provided by operating activities	226,349	142,645
Cash flows from investing activities:
Additions to other property and equipment	(3,329)	(5,444)
Acquisition of oil and natural gas properties	0	(1,338,964)
Additions to oil and natural gas properties	(302,799)	(181,834)
Proceeds from sale of oil and natural gas properties	0	3,605
Proceeds from sale of other property and equipment	76	0
Contributions to equity method investments	(1,569)	(10,673)
Distributions from equity method investments	750	631
Net cash used in investing activities	(306,871)	(1,532,679)
Cash flows from financing activities:
Principal payments on borrowings	(145)
Borrowings on line of credit	200,000	40,000
Borrowings on term loan	0	2,698
Debt issuance costs and loan commitment fees	(280)	(5,733)
Payments on repurchase of stock	(99,997)	0
Proceeds from issuance of common stock, net of offering costs		(5,321)
Net cash provided by financing activities	99,578	31,644
Net increase (decrease) in cash, cash equivalents and restricted cash	19,056	(1,358,390)
Cash, cash equivalents and restricted cash at beginning of period	99,557	1,460,875
Cash, cash equivalents and restricted cash at end of period	118,613	102,485
Supplemental disclosure of cash flow information
Interest payments	7,944	347
Income tax payments	0	0
Supplemental disclosure of non-cash transactions
Capitalized stock-based compensation	1,074	1,021
Asset retirement obligation capitalized	382	6,779
Interest capitalized	843	3,122
Foreign currency translation (loss) gain on equity method investments	$ (5,503)	$ 1,373

Notes to Financial Statements

Notes to Financial Statements	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Notes to Financial Statements	These consolidated financial statements have been prepared by Gulfport Energy Corporation (the “Company” or “Gulfport”) without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), and reflect all adjustments which, in the opinion of management, are necessary for a fair presentation of the results for the interim periods, on a basis consistent with the annual audited consolidated financial statements. All such adjustments are of a normal recurring nature. Certain information, accounting policies, and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the summary of significant accounting policies and notes thereto included in the Company’s most recent annual report on Form 10-K. Results for the three month period ended March 31, 2018 are not necessarily indicative of the results expected for the full year.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Vitruvian Acquisition In December 2016, the Company, through its wholly-owned subsidiary Gulfport MidCon LLC (“Gulfport MidCon”) (formerly known as SCOOP Acquisition Company, LLC), entered into an agreement to acquire certain assets of Vitruvian II Woodford, LLC (“Vitruvian”), an unrelated third-party seller (the “Vitruvian Acquisition”). The assets included in the Vitruvian Acquisition include 46,400 net surface acres located in Grady, Stephens and Garvin Counties, Oklahoma. On February 17, 2017, the Company completed the Vitruvian Acquisition for a total initial purchase price of approximately $1.85 billion , consisting of $1.35 billion in cash, subject to certain adjustments, and approximately 23.9 million shares of the Company’s common stock (of which approximately 5.2 million shares were placed in an indemnity escrow). The cash portion of the purchase price was funded with the net proceeds from the December 2016 common stock and senior note offerings and cash on hand. Acquisition costs of $1.3 million were incurred during the three months ended March 31, 2017 related to the Vitruvian Acquisition. No acquisition costs were incurred during the three months ended March 31, 2018 . Allocation of Purchase Price The Vitruvian Acquisition qualified as a business combination for accounting purposes and, as such, the Company estimated the fair value of the acquired properties as of the February 17, 2017 acquisition date. The fair value of the assets acquired and liabilities assumed was estimated using assumptions that represent Level 3 inputs. See Note 11 for additional discussion of the measurement inputs. The Company estimated that the consideration paid in the Vitruvian Acquisition for these properties approximated the fair value that would be paid by a typical market participant. As a result, no goodwill or bargain purchase gain was recognized in conjunction with the purchase. The following table summarizes the consideration paid by the Company in the Vitruvian Acquisition to acquire the properties and the fair value amount of the assets acquired as of February 17, 2017. (In thousands) Consideration: Cash, net of purchase price adjustments $ 1,354,093 Fair value of Gulfport’s common stock issued 464,639 Total consideration $ 1,818,732 Estimated fair value of identifiable assets acquired and liabilities assumed: Oil and natural gas properties Proved properties $ 362,264 Unproved properties 1,462,957 Asset retirement obligations (6,489 ) Total fair value of net identifiable assets acquired $ 1,818,732 The equity consideration included in the initial purchase price was based on an equity offering price of $20.96 on December 15, 2016. The decrease in the price of Gulfport’s common stock from $20.96 on December 15, 2016 to $19.48 on February 17, 2017 resulted in a decrease to the fair value of the total consideration paid as compared to the initial purchase price of approximately $35.3 million , which resulted in a closing date fair value lower than the initial purchase price. Post-Acquisition Operating Results For the period from the acquisition date of February 17, 2017 to March 31, 2017 , the assets acquired in the Vitruvian Acquisition contributed $26.2 million of revenue to the Company’s consolidated statements of operations. The amount of net income contributed by the assets is impracticable to calculate due to the Company integrating the acquired assets into its overall operations using the full cost method of accounting. Pro Forma Information (Unaudited) The following unaudited pro forma combined financial information presents the Company’s results as though the Vitruvian Acquisition had been completed at January 1, 2017. The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the Vitruvian Acquisition taken place on January 1, 2017; furthermore, the financial information is not intended to be a projection of future results. Three months ended March 31, 2017 (In thousands, except share data) Pro forma revenue $ 368,903 Pro forma net income $ 175,881 Pro forma earnings per share (basic) $ 1.03 Pro forma earnings per share (diluted) $ 1.03

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	PROPERTY AND EQUIPMENT The major categories of property and equipment and related accumulated depletion, depreciation, amortization and impairment as of March 31, 2018 and December 31, 2017 are as follows: March 31, 2018 December 31, 2017 (In thousands) Oil and natural gas properties $ 9,470,697 $ 9,169,156 Office furniture and fixtures 40,236 37,369 Building 44,592 44,565 Land 4,820 4,820 Total property and equipment 9,560,345 9,255,910 Accumulated depletion, depreciation, amortization and impairment (4,264,647 ) (4,153,733 ) Property and equipment, net $ 5,295,698 $ 5,102,177 Under the full cost method of accounting, the Company is required to perform a ceiling test each quarter. The test determines a limit, or ceiling, on the book value of the oil and natural gas properties. At March 31, 2018 , the calculated ceiling was greater than the net book value of the Company’s oil and natural gas properties, thus no ceiling test impairment was required for the three months ended March 31, 2018 . No impairme nt was required for oil and natural gas properties for the three months ended March 31, 2017 . Included in oil and natural gas properties at March 31, 2018 is the cumulative capitalization of $174.4 million in general and administrative costs incurred and capitalized to the full cost pool. General and administrative costs capitalized to the full cost pool represent management’s estimate of costs incurred directly related to exploration and development activities such as geological and other administrative costs associated with overseeing the exploration and development activities. All general and administrative costs not directly associated with exploration and development activities were charged to expense as they were incurred. Capitalized general and administrative costs were approximately $8.8 million and $8.4 million for the three months ended March 31, 2018 and 2017 , respectively. The average depletion rate per Mcfe, which is a function of capitalized costs, future development costs and the related underlying reserves in the periods presented, was $0.93 and $0.84 per Mcfe for the three months ended March 31, 2018 and 2017 , respectively. The following table summarizes the Company’s non-producing properties excluded from amortization by area at March 31, 2018 : March 31, 2018 (In thousands) Utica $ 1,548,121 MidContinent 1,421,853 Niobrara 449 Southern Louisiana 552 Bakken 99 Other 45 $ 2,971,119 At December 31, 2017 , approximately $2.9 billion of non-producing leasehold costs was not subject to amortization. The Company evaluates the costs excluded from its amortization calculation at least annually. Subject to industry conditions and the level of the Company’s activities, the inclusion of most of the above referenced costs into the Company’s amortization calculation typically occurs within three to five years. However, the majority of the Company’s non-producing leases in the Utica Shale have five -year extension terms which could extend this time frame beyond five years. A reconciliation of the Company’s asset retirement obligation for the three months ended March 31, 2018 and 2017 is as follows: March 31, 2018 March 31, 2017 (In thousands) Asset retirement obligation, beginning of period $ 75,100 $ 34,276 Liabilities incurred 329 6,779 Liabilities settled (99 ) — Accretion expense 1,004 282 Revisions in estimated cash flows 53 — Asset retirement obligation as of end of period 76,387 41,337 Less current portion 120 195 Asset retirement obligation, long-term $ 76,267 $ 41,142

Equity Investments

Equity Investments	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	EQUITY INVESTMENTS Investments accounted for by the equity method consist of the following as of March 31, 2018 and December 31, 2017 : Carrying value (Income) loss from equity method investments Approximate ownership % March 31, 2018 December 31, 2017 Three months ended March 31, 2018 2017 (In thousands) Investment in Tatex Thailand II, LLC 23.5 % $ — $ — $ (41 ) $ (243 ) Investment in Grizzly Oil Sands ULC 24.9999 % 53,564 57,641 330 365 Investment in Timber Wolf Terminals LLC 50.0 % 980 983 2 4 Investment in Windsor Midstream LLC 22.5 % 30 30 — (311 ) Investment in Stingray Cementing LLC (1) — % — — — 128 Investment in Blackhawk Midstream LLC 48.5 % — — — — Investment in Stingray Energy Services LLC (1) — % — — — 197 Investment in Sturgeon Acquisitions LLC (1) — % — — — 68 Investment in Mammoth Energy Services, Inc. (1) 25.1 % 179,770 165,715 (13,470 ) 2,158 Investment in Strike Force Midstream LLC 25.0 % 77,350 77,743 (357 ) 2,541 $ 311,694 $ 302,112 $ (13,536 ) $ 4,907 (1) On June 5, 2017, Mammoth Energy Services, Inc. ("Mammoth Energy") acquired Stingray Cementing LLC, Stingray Energy Services LLC and Sturgeon Acquisitions LLC. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding these transactions. The tables below summarize financial information for the Company’s equity investments as of March 31, 2018 and December 31, 2017 . Summarized balance sheet information: March 31, 2018 December 31, 2017 (In thousands) Current assets $ 395,679 $ 415,032 Noncurrent assets $ 2,109,829 $ 1,542,090 Current liabilities $ 285,521 $ 261,086 Noncurrent liabilities $ 87,259 $ 148,839 Summarized results of operations: Three months ended March 31, 2018 2017 (In thousands) Gross revenue $ 511,133 $ 94,478 Net income (loss) $ 64,452 $ (25,339 ) Tatex Thailand II, LLC The Company has an indirect ownership interest in Tatex Thailand II, LLC (“Tatex II”). Tatex II holds an 8.5% interest in APICO, LLC (“APICO”), an international oil and gas exploration company. APICO has a reserve base located in Southeast Asia through its ownership of concessions covering approximately 180,000 acres which includes the Phu Horm Field. The Company received an immaterial amount and $0.2 million in distributions from Tatex II during the three months ended March 31, 2018 and 2017 , respectively. Tatex Thailand III, LLC The Company has an ownership interest in Tatex Thailand III, LLC (“Tatex III”). Tatex III previously owned a concession covering approximately 245,000 acres in Southeast Asia. As of December 31, 2014, the Company reviewed its investment in Tatex III and, together with Tatex III, made the decision to allow the concession to expire in January 2015. As such, the Company fully impaired the asset as of December 31, 2014. In December 2017, Tatex III was dissolved and the Company received a final distribution of $0.2 million . Grizzly Oil Sands ULC The Company, through its wholly owned subsidiary Grizzly Holdings Inc. (“Grizzly Holdings”), owns an interest in Grizzly Oil Sands ULC (“Grizzly”), a Canadian unlimited liability company. The remaining interest in Grizzly is owned by Grizzly Oil Sands Inc. (“Oil Sands”). As of March 31, 2018 , Grizzly had approximately 830,000 acres under lease in the Athabasca, Peace River and Cold Lake oil sands regions of Alberta, Canada. Grizzly has high-graded three oil sands projects to various stages of development. Grizzly commenced commercial production from its Algar Lake Phase I steam-assisted gravity drainage ("SAGD") oil sand project during the second quarter of 2014 and has regulatory approval for up to 11,300 barrels per day of bitumen production. Algar Lake production peaked at 2,200 barrels per day during the ramp-up phase of the SAGD facility, however, in April 2015, Grizzly made the decision to suspend operations at its Algar Lake facility due to the commodity price drop and its effect on project economics. Grizzly continues to monitor market conditions as it assesses start up plans for the facility. The Company reviewed its investment in Grizzly for impairment based on FASB ASC 323 at March 31, 2018 and 2017 and determined no impairment was required. If commodity prices decline in the future however, impairment of the investment in Grizzly may be necessary. During the three months ended March 31, 2018 , Gulfport paid $1.6 million in cash calls. Grizzly’s functional currency is the Canadian dollar. The Company’s investment in Grizzly was decreased by $5.3 million as a result of a foreign currency translation loss and increased by $1.3 million as a result of a foreign currency translation gain for the three months ended March 31, 2018 and 2017 , respectively. Timber Wolf Terminals LLC During 2012, the Company invested in Timber Wolf Terminals LLC (“Timber Wolf”). Timber Wolf was formed to operate a crude/condensate terminal and a sand transloading facility in Ohio. During the three months ended March 31, 2018 and 2017 , the Company paid no cash calls to Timber Wolf. Windsor Midstream LLC At March 31, 2018 , the Company held a 22.5% interest in Windsor Midstream LLC (“Midstream”), an entity controlled and managed by an unrelated third party. Midstream previously owned a 28.4% interest in Coronado Midstream LLC (“Coronado”), a gas processing plant in West Texas. In March 2015, Coronado was sold to EnLink Midstream Partners, LP (“EnLink”). As a result of the sale of Coronado to EnLink, Midstream received common units of EnLink, which were subsequently sold by Midstream. The Company received $0.2 million in distributions from Midstream during the three months ended March 31, 2017 and no distributions during the same period in 2018 . Stingray Cementing LLC During 2012, the Company invested in Stingray Cementing LLC (“Stingray Cementing”). Stingray Cementing provides well cementing services. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. On June 5, 2017 , the Company contributed all of its membership interests in Stingray Cementing to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Blackhawk Midstream LLC During 2012, the Company invested in Blackhawk Midstream LLC (“Blackhawk”). Blackhawk coordinated gathering, compression, processing and marketing activities for the Company in connection with the development of its Utica Shale acreage. Blackhawk does not have any current activities. Stingray Energy Services LLC During 2013, the Company invested in Stingray Energy Services LLC (“Stingray Energy”). Stingray Energy provides rental tools for land-based oil and natural gas drilling, completion and workover activities as well as the transfer of fresh water to wellsites. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. On June 5, 2017 , the Company contributed all of its membership interests in Stingray Energy to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Sturgeon Acquisitions LLC During 2014, the Company invested $20.7 million and received an ownership interest of 25% in Sturgeon Acquisitions LLC (“Sturgeon”). Sturgeon owns and operates sand mines that produce hydraulic fracturing grade sand. On June 5, 2017 , the Company contributed all of its membership interests in Sturgeon to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Mammoth Energy Partners LP/Mammoth Energy Services, Inc. In the fourth quarter of 2014, the Company contributed its investments in four entities to Mammoth Energy Partners LP (“Mammoth”) for a 30.5% interest in this entity. In October 2016, Mammoth converted from a limited partnership into a limited liability company named Mammoth Energy Partners LLC (“Mammoth LLC”) and the Company and the other members of Mammoth LLC contributed their interests in Mammoth LLC to Mammoth Energy. Following the contribution, Mammoth Energy completed its initial public offering of shares of its common stock. On June 5, 2017 , the Company contributed all of its membership interests in Sturgeon (which owns Taylor Frac, LLC, Taylor Real Estate Investments, LLC and South River Road, LLC), Stingray Energy and Stingray Cementing to Mammoth Energy in exchange for approximately 2.0 million shares of Mammoth Energy common stock (the "June 2017 Transactions"). As of March 31, 2018 , the Company held approximately 25.1% of Mammoth Energy’s outstanding common stock. The Company accounted for the transactions as a sale of financial assets under FASB ASC 860. The Company valued the shares of Mammoth Energy common stock it received in the June 2017 Transactions at $18.50 per share, which was the closing price of Mammoth Energy common stock on June 5, 2017 . During the second quarter of 2017, the Company recognized a gain of $12.5 million from the June 2017 Transactions. The Company’s investment in Mammoth Energy was decreased by a $0.2 million foreign currency loss and increased by a $0.1 million foreign currency gain resulting from Mammoth Energy’s foreign subsidiary for the three months ended March 31, 2018 and 2017 , respectively. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. Strike Force Midstream LLC In February 2016, the Company, through its wholly owned subsidiary Gulfport Midstream Holdings, LLC (“Midstream Holdings”), entered into an agreement with Rice Midstream Holdings LLC (“Rice”), a subsidiary of Rice Energy Inc., to develop natural gas gathering assets in eastern Belmont County and Monroe County, Ohio through Strike Force Midstream LLC ("Strike Force"). In 2017, Rice was acquired by EQT Corporation ("EQT"). The Company owns a 25% interest in Strike Force, and EQT acts as operator and owns the remaining 75% interest in Strike Force. Construction of the gathering assets, which is ongoing, provides gathering services for wells operated by Gulfport and other operators and connectivity of existing dry gas gathering systems. During the three months ended March 31, 2018 , Gulfport received distributions of $0.8 million from Strike Force. During the three months ended March 31, 2017 , Gulfport paid $10.0 million in cash calls to Strike Force and received distributions of $0.4 million from Strike Force. The Company has elected to report its proportionate share of Strike Force’s earnings on a one-quarter lag as permitted under FASB ASC 323. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations.

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Variable Interest Entities	VARIABLE INTEREST ENTITIES As of March 31, 2018 , the Company held variable interests in the following variable interest entities (“VIEs”), but was not the primary beneficiary: Midstream and Timber Wolf. These entities have governing provisions that are the functional equivalent of a limited partnership and are considered VIEs because the limited partners or non-managing members lack substantive kick-out or participating rights which causes the equity owners, as a group, to lack a controlling financial interest. The Company is a limited partner or non-managing member in each of these VIEs and is not the primary beneficiary because it does not have a controlling financial interest. The general partner or managing member has power to direct the activities that most significantly impact the VIEs’ economic performance. The Company also held a variable interest in Strike Force due to the fact that it does not have sufficient equity capital at risk. The Company is not the primary beneficiary of this entity. Prior to Mammoth Energy’s IPO, Mammoth LLC was considered a VIE. As a result of the Company’s contribution of its interest in Mammoth LLC to Mammoth Energy in exchange for Mammoth Energy common stock and the completion of Mammoth Energy’s IPO, the Company determined that it no longer held an interest in a VIE. Prior to the contribution of Stingray Energy, Stingray Cementing and Sturgeon to Mammoth Energy, these entities were considered VIEs. As a result of the Company’s contribution of its membership interests in Stingray Energy, Stingray Cementing and Sturgeon to Mammoth Energy in exchange for Mammoth Energy common stock, the Company determined that it no longer held an interest in a VIE. The Company accounts for its investment in these VIEs following the equity method of accounting. The carrying amounts of the Company’s equity investments are classified as other non-current assets on the accompanying consolidated balance sheets. The Company’s maximum exposure to loss as a result of its involvement with these VIEs is based on the Company’s capital contributions and the economic performance of the VIEs, and is equal to the carrying value of the Company’s investments which is the maximum loss the Company could be required to record in the consolidated statements of operations. See Note 3 for further discussion of these entities, including the carrying amounts of each investment.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2018
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	LONG-TERM DEBT Long-term debt consisted of the following items as of March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (In thousands) Revolving credit agreement (1) $ 200,000 $ — 6.625% senior unsecured notes due 2023 (2) 350,000 350,000 6.000% senior unsecured notes due 2024 (3) 650,000 650,000 6.375% senior unsecured notes due 2025 (4) 600,000 600,000 6.375% senior unsecured notes due 2026 (5) 450,000 450,000 Net unamortized debt issuance costs (6) (33,927 ) (34,781 ) Construction loan (7) 23,579 23,724 Less: current maturities of long term debt (629 ) (622 ) Debt reflected as long term $ 2,239,023 $ 2,038,321 The Company capitalized approximately $0.8 million and $3.1 million in interest expense to undeveloped oil and natural gas properties during the three months ended March 31, 2018 and 2017 , respectively. (1) The Company has entered into a senior secured revolving credit facility, as amended, with The Bank of Nova Scotia, as the lead arranger and administrative agent and certain lenders from time to time party thereto. The credit agreement provides for a maximum facility amount of $1.5 billion and matures on December 31, 2021. On March 29, 2017, the Company further amended its revolving credit facility to, among other things, amend the definition of the term EBITDAX to permit pro forma treatment of acquisitions that involve the payment of consideration by Gulfport and its subsidiaries in excess of $50.0 million and of dispositions of property or series of related dispositions of properties that yields gross proceeds to Gulfport or any of its subsidiaries in excess of $50.0 million . On May 4, 2017, the revolving credit facility was further amended to increase the borrowing base from $700.0 million to $1.0 billion , adjust certain of the Company’s investment baskets and add five additional banks to the syndicate. On November 21, 2017, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.5% and (b) add a provision that allows Gulfport to elect a commitment amount (the “Elected Commitment Amount”) that is less than the borrowing base. In connection with this amendment, the borrowing base was set at $1.2 billion , with an elected commitment of $1.0 billion . As of March 31, 2018 , $200.0 million was outstanding under the revolving credit facility and the total availability for future borrowings under this facility, after giving effect to an aggregate of $242.8 million of letters of credit, was $557.2 million . The Company’s wholly-owned subsidiaries have guaranteed the obligations of the Company under the revolving credit facility. Advances under the revolving credit facility may be in the form of either base rate loans or eurodollar loans. The interest rate for base rate loans is equal to (1) the applicable rate, which ranges from 0.50% to 1.50% , plus (2) the highest of: (a) the federal funds rate plus 0.50% , (b) the rate of interest in effect for such day as publicly announced from time to time by agent as its “prime rate,” and (c) the eurodollar rate for an interest period of one month plus 1.00% . The interest rate for eurodollar loans is equal to (1) the applicable rate, which ranges from 1.50% to 2.50% , plus (2) the London interbank offered rate that appears on pages LIBOR01 or LIBOR02 of the Reuters screen that displays such rate for deposits in U.S. dollars, or, if such rate is not available, the rate as administered by ICE Benchmark Administration (or any other person that takes over administration of such rate) per annum equal to the offered rate on such other page or service that displays on average London interbank offered rate as determined by ICE Benchmark Administration (or any other person that takes over administration of such rate) for deposits in U.S. dollars, or, if such rate is not available, the average quotations for three major New York money center banks of whom the agent shall inquire as the “London Interbank Offered Rate” for deposits in U.S. dollars. At March 31, 2018 , amounts borrowed under the credit facility bore interest at the eurodollar rate with a weighted average of 3.52% . The revolving credit facility contains customary negative covenants including, but not limited to, restrictions on the Company’s and its subsidiaries’ ability to: • incur indebtedness; • grant liens; • pay dividends and make other restricted payments; • make investments; • make fundamental changes; • enter into swap contracts; • dispose of assets; • change the nature of their business; and • enter into transactions with affiliates. The negative covenants are subject to certain exceptions as specified in the revolving credit facility. The revolving credit facility also contains certain affirmative covenants, including, but not limited to the following financial covenants: (i) the ratio of net funded debt to EBITDAX (net income, excluding (i) any non-cash revenue or expense associated with swap contracts resulting from ASC 815 and (ii) any cash or non-cash revenue or expense attributable to minority investments plus without duplication and, in the case of expenses, to the extent deducted from revenues in determining net income, the sum of (a) the aggregate amount of consolidated interest expense for such period, (b) the aggregate amount of income, franchise, capital or similar tax expense (other than ad valorem taxes) for such period, (c) all amounts attributable to depletion, depreciation, amortization and asset or goodwill impairment or writedown for such period, (d) all other non-cash charges, (e) exploration costs deducted in determining net income under successful efforts accounting, (f) actual cash distributions received from minority investments, (g) to the extent actually reimbursed by insurance, expenses with respect to liability on casualty events or business interruption, and (h) all reasonable transaction expenses related to dispositions and acquisitions of assets, investments and debt and equity offerings (provided that expenses related to any unsuccessful disposition will be limited to $3.0 million in the aggregate) for a twelve-month period may not be greater than 4.00 to 1.00 ; and (ii) the ratio of EBITDAX to interest expense for a twelve-month period may not be less than 3.00 to 1.00 . The Company was in compliance with its financial covenants at March 31, 2018 . In connection with the Company's 2018 spring redetermination under the revolving credit facility, the lead lenders have proposed to increase the Company's borrowing base from $1.2 billion to $1.4 billion , with an elected commitment of $1.0 billion , and decrease the interest rate by 25 basis points, subject to the approval of the additional required banks within the syndicate. (2) On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of 6.625% Senior Notes due 2023 (the “2023 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2023 Notes Offering”). The Company received net proceeds of approximately $343.6 million after initial purchaser discounts and commissions and estimated offering expenses. The 2023 Notes were issued under an indenture, dated as of April 21, 2015, among the Company, the subsidiary guarantors party thereto and Wells Fargo Bank, National Association, as trustee. In October 2015, the 2023 Notes were exchanged for a new issue of substantially identical debt securities registered under the Securities Act. Pursuant to the indenture relating to the 2023 Notes, interest on the 2023 Notes accrues at a rate of 6.625% per annum on the outstanding principal amount thereof, payable semi-annually on May 1 and November 1 of each year. The 2023 Notes are not guaranteed by Grizzly Holdings, Inc. and will not be guaranteed by any of the Company’s future unrestricted subsidiaries. (3) On October 14, 2016, the Company issued the 2024 Notes in aggregate principal amount of $650.0 million . The 2024 Notes were issued under an indenture, dated as of October 14, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2024 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2024 Notes Offering”). Under the 2024 Indenture, interest on the 2024 Notes accrues at a rate of 6.000% per annum on the outstanding principal amount thereof from October 14, 2016, payable semi-annually on April 15 and October 15 of each year, commencing on April 15, 2017. The 2024 Notes will mature on October 15, 2024. The Company received approximately $638.9 million in net proceeds from the offering of the 2024 Notes, which was used, together with cash on hand, to purchase the then outstanding 2020 Notes in a concurrent cash tender offer, to pay fees and expenses thereof, and to redeem any of the 2020 Notes that remained outstanding after the completion of the tender offer. (4) On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of 6.375% Senior Notes due 2025 (the “2025 Notes”). The 2025 Notes were issued under an indenture, dated as of December 21, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2025 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Under the 2025 Indenture, interest on the 2025 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from December 21, 2016, payable semi-annually on May 15 and November 15 of each year, commencing on May 15, 2017. The 2025 Notes will mature on May 15, 2025. The Company received approximately $584.7 million in net proceeds from the offering of the 2025 Notes, which was used, together with the net proceeds from the Company’s December 2016 common stock offering and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. See “Note 1 – Acquisitions” for additional discussion of the Vitruvian Acquisition. (5) On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of its 6.375% Senior Notes due 2026 (the “2026 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Interest on the 2026 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from October 11, 2017, payable semi-annually on January 15 and July 15 of each year, commencing on January 15, 2018. The 2026 Notes will mature on January 15, 2026. The Company received approximately $444.1 million in net proceeds from the offering of the 2026 Notes, a portion of which was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. (6) Loan issuance costs related to the 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes (collectively the “Notes”) have been presented as a reduction to the Notes. At March 31, 2018 , total unamortized debt issuance costs were $5.0 million for the 2023 Notes, $9.6 million for the 2024 Notes, $13.6 million for the 2025 Notes and $5.5 million for the 2026 Notes. In addition, loan commitment fee costs for the construction loan agreement described immediately below were $0.1 million at March 31, 2018 . (7) On June 4, 2015, the Company entered into a construction loan agreement (the “Construction Loan”) with InterBank for the construction of a new corporate headquarters in Oklahoma City, which was substantially completed in December 2016. The Construction Loan allows for maximum principal borrowings of $24.5 million and required the Company to fund 30% of the cost of the construction before any funds could be drawn, which occurred in January 2016. Interest accrues daily on the outstanding principal balance at a fixed rate of 4.50% per annum and was payable on the last day of the month through May 31, 2017. Starting June 30, 2017, the Company began making monthly payments of principal and interest, with the final payment due June 4, 2025. At March 31, 2018 , the total borrowings under the Construction Loan were approximately $23.6 million .

Common Stock and Changes In Cap

Common Stock and Changes In Capitalization	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Common Stock and Changes in Capitalization	COMMON STOCK AND CHANGES IN CAPITALIZATION Issuance of Common Stock On February 17, 2017, the Company completed the Vitruvian Acquisition for a total initial purchase price of approximately $1.85 billion , consisting of $1.35 billion in cash, subject to certain adjustments, and approximately 23.9 million shares of the Company’s common stock (of which approximately 5.2 million shares are subject to the indemnity escrow). See “Note 1 - Acquisitions” for additional discussion of the Vitruvian Acquisition. Stock Repurchase Program In January 2018, the board of directors of the Company approved a stock repurchase program to acquire up to $100 million of the Company's outstanding stock during 2018. Purchases under the repurchase program may be made from time to time in open market or privately negotiated transactions, and are subject to market conditions, applicable legal requirements, contractual obligations, and other factors. The repurchase program does not require the Company to acquire any specific number of shares. This repurchase program is authorized to extend through December 31, 2018 and may be suspended from time to time, modified, extended, or discontinued by the board of directors at any time. During the three months ended March 31, 2018 , the Company repurchased 9.7 million shares for a total cost of approximately $100.0 million . All repurchased shares have been retired.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2018
Share-based Compensation [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION During the three months ended March 31, 2018 and 2017 , the Company’s stock-based compensation cost was $2.7 million and $2.6 million , respectively, of which the Company capitalized $1.1 million and $1.0 million , respectively, relating to its exploration and development efforts. The following table summarizes restricted stock activity for the three months ended March 31, 2018 : Number of Unvested Restricted Shares Weighted Average Grant Date Fair Value Unvested shares as of January 1, 2018 976,027 $ 18.71 Granted 140,041 8.77 Vested (109,933 ) 21.42 Forfeited (5,937 ) 17.34 Unvested shares as of March 31, 2018 1,000,198 $ 17.03 Unrecognized compensation expense as of March 31, 2018 related to restricted shares was $12.9 million . The expense is expected to be recognized over a weighted average period of 1.53 years.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Reconciliations of the components of basic and diluted net income per common share are presented in the tables below: Three months ended March 31, 2018 2017 Income Shares Per Share Income Shares Per Share (In thousands, except share data) Basic: Net income $ 90,090 180,714,881 $ 0.50 $ 154,455 170,272,685 $ 0.91 Effect of dilutive securities: Stock options and awards — 87,420 — 215,834 Diluted: Net income $ 90,090 180,802,301 $ 0.50 $ 154,455 170,488,519 $ 0.91

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Plugging and Abandonment Funds In connection with the Company’s acquisition in 1997 of the remaining 50% interest in its WCBB properties, the Company assumed the seller’s (Chevron) obligation to contribute approximately $18,000 per month through March 2004 to a plugging and abandonment trust and the obligation to plug a minimum of 20 wells per year for 20 years commencing March 11, 1997. Chevron retained a security interest in production from these properties until the Company’s abandonment obligations to Chevron have been fulfilled. Beginning in 2009, the Company could access the trust for use in plugging and abandonment charges associated with the property, although it has not yet done so. As of March 31, 2018 , the plugging and abandonment trust totaled approximately $3.1 million . At March 31, 2018 , the Company had plugged 551 wells at WCBB since it began its plugging program in 1997, which management believes fulfills its minimum plugging obligation. Operating Leases The Company leases office facilities under non-cancellable operating leases exceeding one year . Future minimum lease commitments under these leases at March 31, 2018 were as follows: (In thousands) Remaining 2018 $ 80 2019 54 Total $ 134 Firm Transportation Commitments The Company had approximately 2,621,000 MMBtu per day of firm sales contracted with third parties. The table below presents these commitments at March 31, 2018 as follows: (MMBtu per day) Remaining 2018 552,000 2019 659,000 2020 526,000 2021 372,000 2022 272,000 Thereafter 240,000 Total 2,621,000 The Company also had approximately $3.7 billion of firm transportation contracted with third parties. The table below presents these commitments at March 31, 2018 as follows: (In thousands) Remaining 2018 $ 186,036 2019 251,644 2020 247,581 2021 246,620 2022 246,620 Thereafter 2,511,853 Total $ 3,690,354 Other Commitments Effective October 1, 2014, the Company entered into a Sand Supply Agreement with Muskie Proppant LLC (“Muskie”), a subsidiary of Mammoth Energy, that expires on September 30, 2018. Pursuant to this agreement, as amended, the Company has agreed to purchase annual and monthly amounts of proppant sand subject to exceptions specified in the agreement at agreed pricing plus agreed costs and expenses. Failure by either Muskie or the Company to deliver or accept the minimum monthly amount results in damages calculated per ton based on the difference between the monthly obligation amount and the amount actually delivered or accepted, as applicable. The Company incurred $0.9 million in non-utilization fees during the three months ended March 31, 2018 . The Company did not incur any non-utilization fees during the three months ended March 31, 2017 . Effective October 1, 2014, the Company entered into an Amended and Restated Master Services Agreement for pressure pumping services with Stingray Pressure Pumping LLC (“Stingray Pressure”), a subsidiary of Mammoth Energy, that expires on September 30, 2018. Pursuant to this agreement, as amended, Stingray Pressure has agreed to provide hydraulic fracturing, stimulation and related completion and rework services to the Company and the Company has agreed to pay Stingray Pressure a monthly service fee plus the associated costs of the services provided. Future minimum commitments under these agreements at March 31, 2018 are $26.2 million . Litigation In two separate complaints, one filed by the State of Louisiana and the Parish of Cameron in the 38th Judicial District Court for the Parish of Cameron on February 9, 2016 and the other filed by the State of Louisiana and the District Attorney for the 15 th Judicial District of the State of Louisiana in the 15 th Judicial District Court for the Parish of Vermillion on July 29, 2016, the Company was named as a defendant, among 26 oil and gas companies, in the Cameron Parish complaint and among more than 40 oil and gas companies in the Vermillion Parish complaint, or the Complaints. The Complaints were filed under the State and Local Coastal Resources Management Act of 1978, as amended, and the rules, regulations, orders and ordinances adopted thereunder, which the Company referred to collectively as the CZM Laws, and allege that certain of the defendants’ oil and gas exploration, production and transportation operations associated with the development of the East Hackberry and West Hackberry oil and gas fields, in the case of the Cameron Parish complaint, and the Tigre Lagoon and Lac Blanc oil and gas fields, in the case of the Vermillion Parish complaint, were conducted in violation of the CZM Laws. The Complaints allege that such activities caused substantial damage to land and waterbodies located in the coastal zone of the relevant Parish, including due to defendants’ design, construction and use of waste pits and the alleged failure to properly close the waste pits and to clear, re-vegetate, detoxify and return the property affected to its original condition, as well as the defendants’ alleged discharge of waste into the coastal zone. The Complaints also allege that the defendants’ oil and gas activities have resulted in the dredging of numerous canals, which had a direct and significant impact on the state coastal waters within the relevant Parish and that the defendants, among other things, failed to design, construct and maintain these canals using the best practical techniques to prevent bank slumping, erosion and saltwater intrusion and to minimize the potential for inland movement of storm-generated surges, which activities allegedly have resulted in the erosion of marshes and the degradation of terrestrial and aquatic life therein. The Complaints also allege that the defendants failed to re-vegetate, refill, clean, detoxify and otherwise restore these canals to their original condition. In these two petitions, the plaintiffs seek damages and other appropriate relief under the CZM Laws, including the payment of costs necessary to clear, re-vegetate, detoxify and otherwise restore the affected coastal zone of the relevant Parish to its original condition, actual restoration of such coastal zone to its original condition, and the payment of reasonable attorney fees and legal expenses and pre-judgment and post judgment interest. The Company was served with the Cameron complaint in early May 2016 and with the Vermillion complaint in early September 2016. The Louisiana Attorney General and the Louisiana Department of Natural Resources intervened in both the Cameron Parish suit and the Vermillion Parish suit. Shortly after the Complaints were filed, certain defendants removed the cases to the lawsuit to the United States District Court for the Western District of Louisiana. In both cases, the plaintiffs filed a motion to remand, and the plaintiffs agreed to an extension of time for all defendants to file responsive pleadings until the District Courts ruled on the motions to remand. In the Vermilion Parish case, the District Court entered an order on September 26, 2017 remanding the lawsuit to the 15th Judicial District Court, State of Louisiana, Parish of Vermilion. In the Cameron Parish lawsuit, the federal magistrate, on January 18, 2018, issued a report and recommendation that the Cameron Parish lawsuit be remanded to the 38th Judicial District Court, State of Louisiana, Parish of Cameron. Due to the procedural posture of lawsuits and that responsive pleadings have not been filed, the parties have not begun discovery and the Company has not had the opportunity to evaluate the applicability of the allegations made in plaintiffs' complaints to the Company's operations, management cannot determine the amount of loss, if any, that may result. In addition, due to the nature of the Company’s business, it is, from time to time, involved in routine litigation or subject to disputes or claims related to its business activities, including workers’ compensation claims and employment related disputes. In the opinion of the Company’s management, none of the pending litigation, disputes or claims against the Company, if decided adversely, will have a material adverse effect on its financial condition, cash flows or results of operations.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2018
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS Natural Gas, Oil and Natural Gas Liquids Derivative Instruments The Company seeks to reduce its exposure to unfavorable changes in natural gas, oil and natural gas liquids prices, which are subject to significant and often volatile fluctuation, by entering into over-the-counter fixed price swaps, basis swaps and various types of option contracts. These contracts allow the Company to predict with greater certainty the effective natural gas, oil and natural gas liquids prices to be received for hedged production and benefit operating cash flows and earnings when market prices are less than the fixed prices provided in the contracts. However, the Company will not benefit from market prices that are higher than the fixed prices in the contracts for hedged production. Fixed price swaps are settled monthly based on differences between the fixed price specified in the contract and the referenced settlement price. When the referenced settlement price is less than the price specified in the contract, the Company receives an amount from the counterparty based on the price difference multiplied by the volume. Similarly, when the referenced settlement price exceeds the price specified in the contract, the Company pays the counterparty an amount based on the price difference multiplied by the volume. The prices contained in these fixed price swaps are based on the NYMEX Henry Hub for natural gas, Argus Louisiana Light Sweet Crude for oil, the NYMEX West Texas Intermediate for oil, and Mont Belvieu for propane and pentane. Below is a summary of the Company’s open fixed price swap positions as of March 31, 2018 . Location Daily Volume (MMBtu/day) Weighted Remaining 2018 NYMEX Henry Hub 927,000 $ 3.02 2019 NYMEX Henry Hub 647,000 $ 2.84 2020 NYMEX Henry Hub 45,000 $ 2.77 Location Daily Volume Weighted Remaining 2018 ARGUS LLS 2,000 $ 56.22 2019 ARGUS LLS 1,000 $ 59.55 Remaining 2018 NYMEX WTI 4,000 $ 53.99 2019 NYMEX WTI 3,000 $ 57.62 Location Daily Volume Weighted Remaining 2018 Mont Belvieu C3 4,000 $ 28.97 2019 Mont Belvieu C3 1,000 $ 27.05 Remaining 2018 Mont Belvieu C5 500 $ 46.62 The Company sold call options and used the associated premiums to enhance the fixed price for a portion of the fixed price natural gas swaps listed above. Each short call option has an established ceiling price. When the referenced settlement price is above the price ceiling established by these short call options, the Company pays its counterparty an amount equal to the difference between the referenced settlement price and the price ceiling multiplied by the hedged contract volumes. Location Daily Volume (MMBtu/day) Weighted Average Price April 2018 - March 2019 NYMEX Henry Hub 50,000 $ 3.13 April 2019 - December 2019 NYMEX Henry Hub 30,000 $ 3.10 For a portion of the natural gas fixed price swaps listed above, the counterparty has an option to extend the original terms an additional twelve months for the period January 2019 through December 2019. The option to extend the terms expires in December 2018. If executed, the Company would have additional fixed price swaps for 100,000 MMBtu per day at a weighted average price of $3.05 per MMBtu. Balance Sheet Presentation The Company reports the fair value of derivative instruments on the consolidated balance sheets as derivative instruments under current assets, noncurrent assets, current liabilities and noncurrent liabilities on a gross basis. The Company determines the current and noncurrent classification based on the timing of expected future cash flows of individual trades. The following table presents the fair value of the Company’s derivative instruments on a gross basis at March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (In thousands) Short-term derivative instruments - asset $ 50,906 $ 78,847 Long-term derivative instruments - asset $ 15,769 $ 8,685 Short-term derivative instruments - liability $ 37,570 $ 32,534 Long-term derivative instruments - liability $ 2,499 $ 2,989 Gains and Losses The following table presents the gain and loss recognized in Net (loss) gain on natural gas, oil and NGL derivatives in the accompanying consolidated statements of operations for the three months ended March 31, 2018 and 2017 . Net (loss) gain on derivative instruments Three months ended March 31, 2018 2017 (In thousands) Natural gas derivatives $ (9,696 ) $ 86,277 Oil derivatives (9,147 ) 10,905 Natural gas liquids derivatives 2,314 2,395 Total $ (16,529 ) $ 99,577 Offsetting of derivative assets and liabilities As noted above, the Company records the fair value of derivative instruments on a gross basis. The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of March 31, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 66,675 $ (27,431 ) $ 39,244 Derivative liabilities $ (40,069 ) $ 27,431 $ (12,638 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 ) Concentration of Credit Risk By using derivative instruments that are not traded on an exchange, the Company is exposed to the credit risk of its counterparties. Credit risk is the risk of loss from counterparties not performing under the terms of the derivative instrument. When the fair value of a derivative instrument is positive, the counterparty is expected to owe the Company, which creates credit risk. To minimize the credit risk in derivative instruments, it is the Company’s policy to enter into derivative contracts only with counterparties that are creditworthy financial institutions deemed by management as competent and competitive market makers. The Company’s derivative contracts are with multiple counterparties to lessen its exposure to any individual counterparty. Additionally, the Company uses master netting agreements to minimize credit risk exposure. The creditworthiness of the Company’s counterparties is subject to periodic review. None of the Company’s derivative instrument contracts contain credit-risk related contingent features. Other than as provided by the Company’s revolving credit facility, the Company is not required to provide credit support or collateral to any of its counterparties under its derivative instruments, nor are the counterparties required to provide credit support to the Company.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Company records certain financial and non-financial assets and liabilities on the balance sheet at fair value in accordance with FASB ASC 820, “Fair Value Measurement and Disclosures” (“FASB ASC 820”). FASB ASC 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. The statement establishes market or observable inputs as the preferred sources of values, followed by assumptions based on hypothetical transactions in the absence of market inputs. The statement requires fair value measurements be classified and disclosed in one of the following categories: Level 1 – Quoted prices in active markets for identical assets and liabilities. Level 2 – Quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar instruments in markets that are not active and model-derived valuations whose inputs are observable or whose significant value drivers are observable. Level 3 – Significant inputs to the valuation model are unobservable. Valuation techniques that maximize the use of observable inputs are favored. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the placement of assets and liabilities within the levels of the fair value hierarchy. Reclassifications of fair value between Level 1, Level 2 and Level 3 of the fair value hierarchy, if applicable, are made at the end of each quarter. The following tables summarize the Company’s financial and non-financial assets and liabilities by FASB ASC 820 valuation level as of March 31, 2018 and December 31, 2017 : March 31, 2018 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 66,675 $ — Liabilities: Derivative Instruments $ — $ 40,069 $ — December 31, 2017 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 87,532 $ — Liabilities: Derivative Instruments $ — $ 35,523 $ — The Company estimates the fair value of all derivative instruments using industry-standard models that consider various assumptions, including current market and contractual prices for the underlying instruments, implied volatility, time value, nonperformance risk, as well as other relevant economic measures. Substantially all of these inputs are observable in the marketplace throughout the full term of the instrument and can be supported by observable data. The estimated fair values of proved oil and natural gas properties assumed in business combinations are based on a discounted cash flow model and market assumptions as to future commodity prices, projections of estimated quantities of oil and natural gas reserves, expectations for timing and amount of future development and operating costs, projections of future rates of production, expected recovery rates and risk-adjusted discount rates. The estimated fair values of unevaluated oil and natural gas properties was based on geological studies, historical well performance, location and applicable mineral lease terms. Based on the unobservable nature of certain of the inputs, the estimated fair value of the oil and gas properties assumed is deemed to use Level 3 inputs. The asset retirement obligations assumed as part of the business combination were estimated using the same assumptions and methodology as described below. See Note 1 for further discussion of the Vitruvian Acquisition. The Company estimates asset retirement obligations pursuant to the provisions of FASB ASC Topic 410, Asset Retirement and Environmental Obligations (“FASB ASC 410”). The initial measurement of asset retirement obligations at fair value is calculated using discounted cash flow techniques and based on internal estimates of future retirement costs associated with oil and gas properties. Given the unobservable nature of the inputs, including plugging costs and reserve lives, the initial measurement of the asset retirement obligation liability is deemed to use Level 3 inputs. See Note 2 for further discussion of the Company’s asset retirement obligations. Asset retirement obligations incurred during the three months ended March 31, 2018 were approximately $0.4 million . The fair value of the common stock received from Mammoth Energy in connection with the Company’s contribution of all of its membership interests in Sturgeon, Stingray Energy and Stingray Cementing was estimated using Level 1 inputs, as the price per share was a quoted price in an active market for identical Mammoth Energy common shares.

Revenue from Contracts with Cus

Revenue from Contracts with Customer (Notes)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customer	REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue Recognition On January 1, 2018, the Company adopted Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers ("ASC 606") using the modified retrospective transition applied to contracts that were not completed as of that date. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606 while prior period amounts are not adjusted and continue to be reported in accordance with historic revenue recognition guidance. The Company’s revenues are primarily derived from the sale of natural gas, oil and condensate and natural gas liquids (“NGLs”). Sales of natural gas, oil and condensate and NGLs are recognized in the period that the performance obligations are satisfied. The Company generally considers the delivery of each unit (MMBtu or Bbl) to be separately identifiable and represents a distinct performance obligation that is satisfied at a point-in-time once control of the product has been transferred to the customer upon delivery to an agreed upon delivery point. The Company considers a variety of facts and circumstances in assessing the point of control transfer, including but not limited to: (i) whether the purchaser can direct the use of the product, (ii) the transfer of significant risks, (iii) the Company’s right to payment and (iv) transfer of legal title. Revenue is measured based on consideration specified in the contract with the customer, and excludes any amounts collected on behalf of third parties. These contracts typically include variable consideration that is based on pricing tied to market indices and volumes delivered in the current month. The payment date is usually within 30 days of the end of the calendar month in which the commodity is delivered. The recognition of gains or losses on derivative instruments is outside the scope of ASC 606 and is not considered revenue from contracts with customers subject to ASC 606. The Company may use financial or physical contracts accounted for as derivatives as economic hedges to manage price risk associated with normal sales, or in limited cases may use them for contracts the Company intends to physically settle but do not meet all of the criteria to be treated as normal sales. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, and that are collected by the Company from a customer, are excluded from revenue. Transaction Price Allocated to Remaining Performance Obligations A significant number of the Company's product sales are short-term in nature generally through evergreen contracts with contract terms of one year or less. These contracts typically automatically renew under the same provisions. For those contracts, the Company has utilized the practical expedient allowed in the new revenue accounting standard that exempts the Company from disclosure of the transaction price allocated to remaining performance obligations if the performance obligation is part of a contract that has an original expected duration of one year or less. For product sales that have a contract term greater than one year, the Company has utilized the practical expedient that exempts the Company from disclosure of the transaction price allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation. Under these sales contracts, each unit of product generally represents a separate performance obligation; therefore, future volumes are wholly unsatisfied and disclosure of the transaction price allocated to remaining performance obligations is not required. Currently, the Company's product sales that have a contractual term greater than one year have no long-term fixed consideration. Contract Balances Receivables from contracts with customers are recorded when the right to consideration becomes unconditional, generally when control of the product has been transferred to the customer. Receivables from contracts with customers were $125.8 million and $135.0 million as of March 31, 2018 and December 31, 2017, respectively, and are reported in accounts receivable - oil and natural gas on the consolidated balance sheet. The Company currently has no assets or liabilities related to its revenue contracts, including no upfront or rights to deficiency payments. Contract Modifications For contracts modified prior to the beginning of the earliest reporting period presented under ASC 606, the Company has elected to reflect the aggregate of the effect of all modifications that occurred before the beginning of the earliest period presented under the new standard when identifying the satisfied and unsatisfied performance obligations, determining the transaction price and allocating the transaction price to the satisfied and unsatisfied performance obligations for the modified contracts at transition. Prior-Period Performance Obligations The Company records revenue in the month production is delivered to the purchaser. However, settlement statements for certain gas and NGLs sales may be received for 30 to 90 days after the date production is delivered, and as a result, the Company is required to estimate the amount of production that was delivered to the purchaser and the price that will be received for the sale of the product. The differences between the estimates and the actual amounts for product sales is recorded in the month that payment is received from the purchaser. The Company has internal controls in place for the estimation process and any identified differences between revenue estimates and actual revenue received historically have not been significant. For the three months ended March 31, 2018, revenue recognized in the reporting period related to performance obligations satisfied in prior reporting periods was not material.

Income Taxes (Notes)

Income Taxes (Notes)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES On December 22, 2017, the President of the United States signed into law Public Law No. 115-97, a comprehensive tax reform bill commonly referred to as the Tax Cuts and Jobs Act, or the Tax Act, that significantly reformed the Internal Revenue Code of 1986, as amended. The Tax act substantially revised numerous areas of U.S. federal income tax law, including reducing the maximum corporate income tax rate from 35% to 21%, allowing for full expensing of certain capital expenditures, modifying the limitations on the utilization of net operating losses, and repealing the corporate alternative minimum tax. The various estimates included in determining the Company's tax provision as of December 31, 2017 remain provisional through the three months ended March 31, 2018 and may be adjusted through subsequent events such as the filing of its 2017 consolidated federal income tax return and the issuance of additional guidance from the Internal Revenue Service or from state tax authorities. There were no material changes to the provisional estimates during the quarter ended March 31, 2018 .

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2018
Investments, All Other Investments [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying amounts on the accompanying consolidated balance sheet for cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and current debt are carried at cost, which approximates market value due to their short-term nature. Long-term debt related to the Construction Loan is carried at cost, which approximates market value based on the borrowing rates currently available to the Company with similar terms and maturities. At March 31, 2018 , the carrying value of the outstanding debt represented by the Notes was approximately $2.0 billion , including the unamortized debt issuance cost of approximately $5.0 million related to the 2023 Notes, approximately $9.6 million related to the 2024 Notes, approximately $13.6 million related to the 2025 Notes and approximately $5.5 million related to the 2026 Notes. Based on the quoted market price, the fair value of the Notes was determined to be approximately $2.0 billion at March 31, 2018 .

Condensed Consolidating Financi

Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2018
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Financial Information	CONDENSED CONSOLIDATING FINANCIAL INFORMATION On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of the 2023 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. In connection with the 2023 Notes Offering, the Company and its subsidiary guarantors entered into a registration rights agreement, dated as of April 21, 2015, pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2023 Notes for a new issue of substantially identical debt securities registered under the Securities Act. The exchange offer for the 2023 Notes was completed on October 13, 2015. On October 14, 2016, the Company issued $650.0 million in aggregate principal amount of the 2024 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. The net proceeds from the issuance of the 2024 Notes, together with cash on hand, were used to repurchase or redeem all of the then-outstanding 2020 Notes in October 2016. On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of the 2025 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. The Company used the net proceeds from the issuance of the 2025 Notes, together with the net proceeds from the December 2016 underwritten offering of the Company’s common stock and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. In connection with the 2024 Notes and the 2025 Notes Offerings, the Company and its subsidiary guarantors entered into two registration rights agreements, pursuant to which the Company agreed to file a registration statement with respect to offers to exchange the 2024 Notes and the 2025 Notes for new issues of substantially identical debt securities registered under the Securities Act. The exchange offers for the 2024 Notes and the 2025 Notes were completed on September 13, 2017. On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of the 2026 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. A portion of the net proceeds from the issuance of the 2026 Notes was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. The 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes are guaranteed on a senior unsecured basis by all existing consolidated subsidiaries that guarantee the Company’s secured revolving credit facility or certain other debt (the “Guarantors”). The 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes are not guaranteed by Grizzly Holdings, Inc. (the “Non-Guarantor”). The Guarantors are 100% owned by Gulfport (the “Parent”), and the guarantees are full, unconditional, joint and several. There are no significant restrictions on the ability of the Parent or the Guarantors to obtain funds from each other in the form of a dividend or loan. The following condensed consolidating balance sheets, statements of operations, statements of comprehensive income (loss) and statements of cash flows are provided for the Parent, the Guarantors and the Non-Guarantor and include the consolidating adjustments and eliminations necessary to arrive at the information for the Company on a condensed consolidated basis. The information has been presented using the equity method of accounting for the Parent’s ownership of the Guarantors and the Non-Guarantor. CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 81,357 $ 37,254 $ 2 $ — $ 118,613 Accounts receivable - oil and natural gas 133,387 66,070 — — 199,457 Accounts receivable - intercompany 585,111 64,492 — (649,603 ) — Prepaid expenses and other current assets 6,115 1,449 — — 7,564 Short-term derivative instruments 50,906 — — — 50,906 Total current assets 856,876 169,265 2 (649,603 ) 376,540 Property and equipment: Oil and natural gas properties, full-cost accounting 6,769,164 2,702,262 — (729 ) 9,470,697 Other property and equipment 89,597 51 — — 89,648 Accumulated depletion, depreciation, amortization and impairment (4,264,609 ) (38 ) — — (4,264,647 ) Property and equipment, net 2,594,152 2,702,275 — (729 ) 5,295,698 Other assets: Equity investments and investments in subsidiaries 2,458,237 77,350 53,563 (2,277,456 ) 311,694 Long-term derivative instruments 15,769 — — — 15,769 Deferred tax asset — — — — — Inventories 6,045 2,460 — — 8,505 Other assets 13,569 6,617 — — 20,186 Total other assets 2,493,620 86,427 53,563 (2,277,456 ) 356,154 Total assets $ 5,944,648 $ 2,957,967 $ 53,565 $ (2,927,788 ) $ 6,028,392 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 443,963 $ 133,585 $ — $ — $ 577,548 Accounts payable - intercompany 64,980 584,495 128 (649,603 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 37,570 — — — 37,570 Current maturities of long-term debt 629 — — — 629 Total current liabilities 547,262 718,080 128 (649,603 ) 615,867 Long-term derivative instruments 2,499 — — — 2,499 Asset retirement obligation - long-term 64,091 12,176 — — 76,267 Deferred tax liability 2,884 — — — 2,884 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,239,023 — — — 2,239,023 Total liabilities 2,855,759 733,219 128 (649,603 ) 2,939,503 Stockholders’ equity: Common stock 1,735 — — — 1,735 Paid-in capital 4,319,034 1,915,598 260,877 (2,176,475 ) 4,319,034 Accumulated other comprehensive (loss) income (46,042 ) — (43,909 ) 43,909 (46,042 ) Retained (deficit) earnings (1,185,838 ) 309,150 (163,531 ) (145,619 ) (1,185,838 ) Total stockholders’ equity 3,088,889 2,224,748 53,437 (2,278,185 ) 3,088,889 Total liabilities and stockholders ’ equity $ 5,944,648 $ 2,957,967 $ 53,565 $ (2,927,788 ) $ 6,028,392 CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) December 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 67,908 $ 31,649 $ — $ — $ 99,557 Accounts receivable - oil and natural gas 128,121 54,092 — — 182,213 Accounts receivable - intercompany 554,439 63,374 — (617,813 ) — Prepaid expenses and other current assets 4,719 193 — — 4,912 Short-term derivative instruments 78,847 — — — 78,847 Total current assets 834,034 149,308 — (617,813 ) 365,529 Property and equipment: Oil and natural gas properties, full-cost accounting, 6,562,147 2,607,738 — (729 ) 9,169,156 Other property and equipment 86,711 43 — — 86,754 Accumulated depletion, depreciation, amortization and impairment (4,153,696 ) (37 ) — — (4,153,733 ) Property and equipment, net 2,495,162 2,607,744 — (729 ) 5,102,177 Other assets: Equity investments and investments in subsidiaries 2,361,575 77,744 57,641 (2,194,848 ) 302,112 Long-term derivative instruments 8,685 — — — 8,685 Deferred tax asset 1,208 — — — 1,208 Inventories 5,816 2,411 — — 8,227 Other assets 12,483 7,331 — — 19,814 Total other assets 2,389,767 87,486 57,641 (2,194,848 ) 340,046 Total assets $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 416,249 $ 137,361 $ — $ (1 ) $ 553,609 Accounts payable - intercompany 63,373 554,313 127 (617,813 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 32,534 — — — 32,534 Current maturities of long-term debt 622 — — — 622 Total current liabilities 512,898 691,674 127 (617,814 ) 586,885 Long-term derivative instruments 2,989 — — — 2,989 Asset retirement obligation - long-term 63,141 11,839 — — 74,980 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,038,321 — — — 2,038,321 Total liabilities 2,617,349 706,476 127 (617,814 ) 2,706,138 Stockholders’ equity: Common stock 1,831 — — — 1,831 Paid-in capital 4,416,250 1,915,598 259,307 (2,174,905 ) 4,416,250 Accumulated other comprehensive (loss) income (40,539 ) — (38,593 ) 38,593 (40,539 ) Retained (deficit) earnings (1,275,928 ) 222,464 (163,200 ) (59,264 ) (1,275,928 ) Total stockholders’ equity 3,101,614 2,138,062 57,514 (2,195,576 ) 3,101,614 Total liabilities and stockholders ’ equity $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 213,561 $ 111,831 $ — $ — $ 325,392 Costs and expenses: Lease operating expenses 13,831 5,075 — — 18,906 Production taxes 4,011 2,843 — — 6,854 Midstream gathering and processing 45,666 18,527 — — 64,193 Depreciation, depletion and amortization 111,017 1 — — 111,018 General and administrative 13,811 (713 ) 1 — 13,099 Accretion expense 790 214 — — 1,004 Acquisition expense — — — — — 189,126 25,947 1 — 215,074 INCOME (LOSS) FROM OPERATIONS 24,435 85,884 (1 ) — 110,318 OTHER (INCOME) EXPENSE: Interest expense 34,393 (428 ) — — 33,965 Interest income (31 ) (6 ) — — (37 ) (Income) loss from equity method investments and investments in subsidiaries (99,864 ) (357 ) 330 86,355 (13,536 ) Other income (84 ) (11 ) — — (95 ) (65,586 ) (802 ) 330 86,355 20,297 INCOME (LOSS) BEFORE INCOME TAXES 90,021 86,686 (331 ) (86,355 ) 90,021 INCOME TAX BENEFIT (69 ) — — — (69 ) NET INCOME (LOSS) $ 90,090 $ 86,686 $ (331 ) $ (86,355 ) $ 90,090 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 272,441 $ 60,563 $ — $ — $ 333,004 Costs and expenses: Lease operating expenses 17,449 1,854 — — 19,303 Production taxes 3,102 804 — — 3,906 Midstream gathering and processing 37,724 10,217 — — 47,941 Depreciation, depletion and amortization 65,990 1 — — 65,991 General and administrative 12,874 (275 ) 1 — 12,600 Accretion expense 282 — — — 282 Acquisition expense — 1,298 — — 1,298 137,421 13,899 1 — 151,321 INCOME (LOSS) FROM OPERATIONS 135,020 46,664 (1 ) — 181,683 OTHER (INCOME) EXPENSE: Interest expense 25,048 (1,569 ) — — 23,479 Interest income (842 ) — — — (842 ) (Income) loss from equity method investments and investments in subsidiaries (42,614 ) 2,541 365 44,615 4,907 Other (income) expense (1,027 ) (189 ) — 900 (316 ) (19,435 ) 783 365 45,515 27,228 INCOME (LOSS) BEFORE INCOME TAXES 154,455 45,881 (366 ) (45,515 ) 154,455 INCOME TAX EXPENSE — — — — — NET INCOME (LOSS) $ 154,455 $ 45,881 $ (366 ) $ (45,515 ) $ 154,455 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 90,090 $ 86,686 $ (331 ) $ (86,355 ) $ 90,090 Foreign currency translation adjustment (5,503 ) (187 ) (5,316 ) 5,503 (5,503 ) Other comprehensive (loss) income (5,503 ) (187 ) (5,316 ) 5,503 (5,503 ) Comprehensive income (loss) $ 84,587 $ 86,499 $ (5,647 ) $ (80,852 ) $ 84,587 Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 154,455 $ 45,881 $ (366 ) $ (45,515 ) $ 154,455 Foreign currency translation adjustment 1,373 55 1,318 (1,373 ) 1,373 Other comprehensive income (loss) 1,373 55 1,318 (1,373 ) 1,373 Comprehensive income (loss) $ 155,828 $ 45,936 $ 952 $ (46,888 ) $ 155,828 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by operating activities $ 144,895 $ 81,452 $ 1 $ 1 $ 226,349 Net cash (used in) provided by investing activities (231,024 ) (75,847 ) (1,569 ) 1,569 (306,871 ) Net cash provided by (used in) financing activities 99,578 — 1,570 (1,570 ) 99,578 Net increase in cash, cash equivalents and restricted cash 13,449 5,605 2 — 19,056 Cash, cash equivalents and restricted cash at beginning of period 67,908 31,649 — — 99,557 Cash, cash equivalents and restricted cash at end of period $ 81,357 $ 37,254 $ 2 $ — $ 118,613 Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by operating activities $ 139,260 $ 3,384 $ 1 $ — $ 142,645 Net cash (used in) provided by investing activities (1,557,852 ) (1,348,964 ) (673 ) 1,374,810 (1,532,679 ) Net cash provided by (used in) financing activities 31,644 1,374,137 673 (1,374,810 ) 31,644 Net (decrease) increase in cash, cash equivalents and restricted cash (1,386,948 ) 28,557 1 — (1,358,390 ) Cash, cash equivalents and restricted cash at beginning of period 1,458,882 1,993 — — 1,460,875 Cash, cash equivalents and restricted cash at end of period $ 71,934 $ 30,550 $ 1 $ — $ 102,485

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS In May 2014 , the Financial Accounting Standards Board (“FASB”) issued ASC 606 . ASC 606 supersedes existing industry specific revenue recognition guidance and increases disclosure requirements. The core principle of the new standard is for the recognition of revenue to depict the transfer of goods or services to customers in amounts that reflect the payment to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 as of January 1, 2018 using the modified retrospective transition method applied to contracts that were not completed as of that date. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue standard. Under the modified retrospective method, the Company recognizes the cumulative effect of initially applying the new revenue standard as an adjustment to the opening balance of retained earnings; however, no adjustment was required as a result of adopting the new revenue standard. The comparative information has not been restated and continues to be reported under the historic accounting standards in effect for those periods. The impact of the adoption of the new revenue standard is not expected to be material to the Company’s net income on an ongoing basis. In February 2016 , the FASB issued ASU No. 2016-02 , Leases . The standard updates the previous lease guidance by requiring the lessee to recognize a right-to-use asset and lease liability on the balance sheet for all leases with lease terms of more than 12 months. The accounting for lessors is largely unchanged. The guidance is effective for periods after December 15, 2018 , with a modified retrospective approach to be used for implementation. The Company will not early adopt this standard, and will apply the revised lease rules for its interim and annual reporting periods starting January 1, 2019. The Company is in the process of evaluating the impact of this guidance on its consolidated financial statements and related disclosures by performing an impact assessment to analyze the population of arrangements that meet the definition of a lease under the new standard. This analysis could result in an impact to the Company's financial statements; however, that impact is currently not known. Additionally, in January 2018 , the FASB issued ASU No. 2018-01 , Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 . The amendments in this update provide an optional transition to not evaluate existing or expired land easements that were not previously accounted for under current leases guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements beginning at the date of adoption. An entity that does not elect this practical expedient should evaluate all existing or expired land easements in connection with the adoption of the new lease requirement in Topic 842 to assess whether they meet the definition of a lease. The Company is currently evaluating this guidance to determine whether or not to make use of this practical expedient. In June 2016 , the FASB issued ASU No. 2016-13 , Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . This ASU amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this ASU eliminates the probable initial recognition threshold in current GAAP and instead, requires an entity to reflect its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposure, reinsurance receivables and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for periods after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its financial statements and related disclosures and does not anticipate it to have a material effect. In August 2016 , the FASB issued ASU No. 2016-15 , Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments . This ASU clarifies how certain cash receipts and cash payments should be classified and presented in the statement of cash flows. The Company adopted this standard in the first quarter of 2018 and has made an accounting policy election to classify distributions received from equity method investees using the nature of the distribution approach, which classifies distributions received from investees as either cash inflows from operating activities or cash inflows from investing activities in the statement of cash flows based on the nature of the activities of the investee that generated the distribution. The impact of adopting this ASU was not material to prior periods presented. In November 2016 , the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash This ASU requires that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows and to provide a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. The Company adopted this standard in the first quarter of 2018 using the retrospective transition method. The adoption of this standard had no impact on the statement of cash flows for the three months ended March 31, 2018 and resulted in the addition of $185.0 million of restricted cash to the beginning cash balance and an increase to net cash used in investing activities by the same amount on the statement of cash flows for the three months ended March 31, 2017 . In January 2017 , the FASB issued ASU No. 2017-01 , Clarifying the Definition of a Business . Under the current business combination guidance, there are three elements of a business: inputs, processes and outputs. The revised guidance adds an initial screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single asset or group of similar assets. If that screen is met, the set of assets is not a business. The new framework also specifies the minimum required inputs and processes necessary to be a business. The Company adopted this standard in the first quarter of 2018 with no significant effect on its financial statements or related disclosures. In February 2018 , the FASB issued ASU No. 2018-02 , Income statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows a reclassification from accumulated other comprehensive income to retained earnings for standard tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendment will be effective for reporting periods beginning after December 15, 2018 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Derivatives In April 2018, the Company entered into fixed price swaps for 2018 for approximately 53,000 MMBtu of natural gas per day at a weighted average price of $2.84 per MMBtu. For 2019, the Company entered into fixed price swaps for approximately 15,000 MMBtu of natural gas per day at a weighted average price of $2.76 per MMBtu, for approximately 1,000 Bbls of oil per day at a weighted average price of $60.24 per Bbl, for approximately 2,000 Bbls of C3 propane per day at a weighted average price of $28.04 per Bbl and for approximately 500 Bbls of C5 pentane per day at a weighted average price of $54.08 per Bbl. For 2020, the Company entered into fixed price swaps for approximately 5,000 MMBtu of natural gas per day at a weighted average price of $2.76 per MMBtu. The Company’s fixed price swap contracts are tied to the commodity prices on NYMEX Henry Hub for natural gas, NYMEX WTI for oil, and Mont Belvieu for propane and pentane. The Company will receive the fixed price amount stated in the contract and pay to its counterparty the current market price as listed on NYMEX for natural gas and oil or Mont Belvieu for propane and pentane. Sale of Equity Interest in Strike Force Midstream LLC On May 1, 2018, the Company sold its 25% equity interest in Strike Force to EQT Midstream Partners, LP for $175.0 million in cash. Expanded Share Repurchase Program In May 2018, Gulfport 's board of directors authorized the expansion of its stock repurchase program, authorizing the Company to acquire up to an additional $100 million of its outstanding common stock during 2018 for a total of up to $200 million . Purchases under the expanded repurchase program may be made from time to time in open market or privately negotiated transactions, and will be subject to market conditions, applicable legal requirements, contractual obligations and other factors. The repurchase program does not require the Company to acquire any specific number of shares. The Company intends to purchase shares under the repurchase program opportunistically with available funds while maintaining sufficient liquidity to fund its 2018 capital development program. This repurchase program is authorized to extend through December 31, 2018 and may be suspended from time to time, modified, extended or discontinued by the board of directors at any time.

Recent Accounting Pronounceme26

Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Variable Interest Entities	The Company accounts for its investment in these VIEs following the equity method of accounting. The carrying amounts of the Company’s equity investments are classified as other non-current assets on the accompanying consolidated balance sheets. The Company’s maximum exposure to loss as a result of its involvement with these VIEs is based on the Company’s capital contributions and the economic performance of the VIEs, and is equal to the carrying value of the Company’s investments which is the maximum loss the Company could be required to record in the consolidated statements of operations. See Note 3 for further discussion of these entities, including the carrying amounts of each investment.
Recent Accounting Pronouncements	In May 2014 , the Financial Accounting Standards Board (“FASB”) issued ASC 606 . ASC 606 supersedes existing industry specific revenue recognition guidance and increases disclosure requirements. The core principle of the new standard is for the recognition of revenue to depict the transfer of goods or services to customers in amounts that reflect the payment to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 as of January 1, 2018 using the modified retrospective transition method applied to contracts that were not completed as of that date. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue standard. Under the modified retrospective method, the Company recognizes the cumulative effect of initially applying the new revenue standard as an adjustment to the opening balance of retained earnings; however, no adjustment was required as a result of adopting the new revenue standard. The comparative information has not been restated and continues to be reported under the historic accounting standards in effect for those periods. The impact of the adoption of the new revenue standard is not expected to be material to the Company’s net income on an ongoing basis. In February 2016 , the FASB issued ASU No. 2016-02 , Leases . The standard updates the previous lease guidance by requiring the lessee to recognize a right-to-use asset and lease liability on the balance sheet for all leases with lease terms of more than 12 months. The accounting for lessors is largely unchanged. The guidance is effective for periods after December 15, 2018 , with a modified retrospective approach to be used for implementation. The Company will not early adopt this standard, and will apply the revised lease rules for its interim and annual reporting periods starting January 1, 2019. The Company is in the process of evaluating the impact of this guidance on its consolidated financial statements and related disclosures by performing an impact assessment to analyze the population of arrangements that meet the definition of a lease under the new standard. This analysis could result in an impact to the Company's financial statements; however, that impact is currently not known. Additionally, in January 2018 , the FASB issued ASU No. 2018-01 , Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 . The amendments in this update provide an optional transition to not evaluate existing or expired land easements that were not previously accounted for under current leases guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements beginning at the date of adoption. An entity that does not elect this practical expedient should evaluate all existing or expired land easements in connection with the adoption of the new lease requirement in Topic 842 to assess whether they meet the definition of a lease. The Company is currently evaluating this guidance to determine whether or not to make use of this practical expedient. In June 2016 , the FASB issued ASU No. 2016-13 , Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . This ASU amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this ASU eliminates the probable initial recognition threshold in current GAAP and instead, requires an entity to reflect its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposure, reinsurance receivables and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for periods after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its financial statements and related disclosures and does not anticipate it to have a material effect. In August 2016 , the FASB issued ASU No. 2016-15 , Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments . This ASU clarifies how certain cash receipts and cash payments should be classified and presented in the statement of cash flows. The Company adopted this standard in the first quarter of 2018 and has made an accounting policy election to classify distributions received from equity method investees using the nature of the distribution approach, which classifies distributions received from investees as either cash inflows from operating activities or cash inflows from investing activities in the statement of cash flows based on the nature of the activities of the investee that generated the distribution. The impact of adopting this ASU was not material to prior periods presented. In November 2016 , the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash This ASU requires that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows and to provide a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. The Company adopted this standard in the first quarter of 2018 using the retrospective transition method. The adoption of this standard had no impact on the statement of cash flows for the three months ended March 31, 2018 and resulted in the addition of $185.0 million of restricted cash to the beginning cash balance and an increase to net cash used in investing activities by the same amount on the statement of cash flows for the three months ended March 31, 2017 . In January 2017 , the FASB issued ASU No. 2017-01 , Clarifying the Definition of a Business . Under the current business combination guidance, there are three elements of a business: inputs, processes and outputs. The revised guidance adds an initial screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single asset or group of similar assets. If that screen is met, the set of assets is not a business. The new framework also specifies the minimum required inputs and processes necessary to be a business. The Company adopted this standard in the first quarter of 2018 with no significant effect on its financial statements or related disclosures. In February 2018 , the FASB issued ASU No. 2018-02 , Income statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows a reclassification from accumulated other comprehensive income to retained earnings for standard tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendment will be effective for reporting periods beginning after December 15, 2018 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures.

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the consideration paid by the Company in the Vitruvian Acquisition to acquire the properties and the fair value amount of the assets acquired as of February 17, 2017. (In thousands) Consideration: Cash, net of purchase price adjustments $ 1,354,093 Fair value of Gulfport’s common stock issued 464,639 Total consideration $ 1,818,732 Estimated fair value of identifiable assets acquired and liabilities assumed: Oil and natural gas properties Proved properties $ 362,264 Unproved properties 1,462,957 Asset retirement obligations (6,489 ) Total fair value of net identifiable assets acquired $ 1,818,732
Schedule of Pro Forma Information	The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the Vitruvian Acquisition taken place on January 1, 2017; furthermore, the financial information is not intended to be a projection of future results. Three months ended March 31, 2017 (In thousands, except share data) Pro forma revenue $ 368,903 Pro forma net income $ 175,881 Pro forma earnings per share (basic) $ 1.03 Pro forma earnings per share (diluted) $ 1.03

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	The major categories of property and equipment and related accumulated depletion, depreciation, amortization and impairment as of March 31, 2018 and December 31, 2017 are as follows: March 31, 2018 December 31, 2017 (In thousands) Oil and natural gas properties $ 9,470,697 $ 9,169,156 Office furniture and fixtures 40,236 37,369 Building 44,592 44,565 Land 4,820 4,820 Total property and equipment 9,560,345 9,255,910 Accumulated depletion, depreciation, amortization and impairment (4,264,647 ) (4,153,733 ) Property and equipment, net $ 5,295,698 $ 5,102,177
Summary of Non-producing Properties Excluded from Amortization by Area	The following table summarizes the Company’s non-producing properties excluded from amortization by area at March 31, 2018 : March 31, 2018 (In thousands) Utica $ 1,548,121 MidContinent 1,421,853 Niobrara 449 Southern Louisiana 552 Bakken 99 Other 45 $ 2,971,119
Schedule of Asset Retirement Obligation	A reconciliation of the Company’s asset retirement obligation for the three months ended March 31, 2018 and 2017 is as follows: March 31, 2018 March 31, 2017 (In thousands) Asset retirement obligation, beginning of period $ 75,100 $ 34,276 Liabilities incurred 329 6,779 Liabilities settled (99 ) — Accretion expense 1,004 282 Revisions in estimated cash flows 53 — Asset retirement obligation as of end of period 76,387 41,337 Less current portion 120 195 Asset retirement obligation, long-term $ 76,267 $ 41,142

Equity Investments (Tables)

Equity Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments Accounted for by the Equity Method	Investments accounted for by the equity method consist of the following as of March 31, 2018 and December 31, 2017 : Carrying value (Income) loss from equity method investments Approximate ownership % March 31, 2018 December 31, 2017 Three months ended March 31, 2018 2017 (In thousands) Investment in Tatex Thailand II, LLC 23.5 % $ — $ — $ (41 ) $ (243 ) Investment in Grizzly Oil Sands ULC 24.9999 % 53,564 57,641 330 365 Investment in Timber Wolf Terminals LLC 50.0 % 980 983 2 4 Investment in Windsor Midstream LLC 22.5 % 30 30 — (311 ) Investment in Stingray Cementing LLC (1) — % — — — 128 Investment in Blackhawk Midstream LLC 48.5 % — — — — Investment in Stingray Energy Services LLC (1) — % — — — 197 Investment in Sturgeon Acquisitions LLC (1) — % — — — 68 Investment in Mammoth Energy Services, Inc. (1) 25.1 % 179,770 165,715 (13,470 ) 2,158 Investment in Strike Force Midstream LLC 25.0 % 77,350 77,743 (357 ) 2,541 $ 311,694 $ 302,112 $ (13,536 ) $ 4,907 (1) On June 5, 2017, Mammoth Energy Services, Inc. ("Mammoth Energy") acquired Stingray Cementing LLC, Stingray Energy Services LLC and Sturgeon Acquisitions LLC. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding these transactions.
Equity Method Investment Balance Sheet Summary	The tables below summarize financial information for the Company’s equity investments as of March 31, 2018 and December 31, 2017 . Summarized balance sheet information: March 31, 2018 December 31, 2017 (In thousands) Current assets $ 395,679 $ 415,032 Noncurrent assets $ 2,109,829 $ 1,542,090 Current liabilities $ 285,521 $ 261,086 Noncurrent liabilities $ 87,259 $ 148,839
Equity Method Investment Income Statement Summary	Summarized results of operations: Three months ended March 31, 2018 2017 (In thousands) Gross revenue $ 511,133 $ 94,478 Net income (loss) $ 64,452 $ (25,339 )

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Long-term Debt, Unclassified [Abstract]
Summary of Long-Term Debt	Long-term debt consisted of the following items as of March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (In thousands) Revolving credit agreement (1) $ 200,000 $ — 6.625% senior unsecured notes due 2023 (2) 350,000 350,000 6.000% senior unsecured notes due 2024 (3) 650,000 650,000 6.375% senior unsecured notes due 2025 (4) 600,000 600,000 6.375% senior unsecured notes due 2026 (5) 450,000 450,000 Net unamortized debt issuance costs (6) (33,927 ) (34,781 ) Construction loan (7) 23,579 23,724 Less: current maturities of long term debt (629 ) (622 ) Debt reflected as long term $ 2,239,023 $ 2,038,321 The Company capitalized approximately $0.8 million and $3.1 million in interest expense to undeveloped oil and natural gas properties during the three months ended March 31, 2018 and 2017 , respectively. (1) The Company has entered into a senior secured revolving credit facility, as amended, with The Bank of Nova Scotia, as the lead arranger and administrative agent and certain lenders from time to time party thereto. The credit agreement provides for a maximum facility amount of $1.5 billion and matures on December 31, 2021. On March 29, 2017, the Company further amended its revolving credit facility to, among other things, amend the definition of the term EBITDAX to permit pro forma treatment of acquisitions that involve the payment of consideration by Gulfport and its subsidiaries in excess of $50.0 million and of dispositions of property or series of related dispositions of properties that yields gross proceeds to Gulfport or any of its subsidiaries in excess of $50.0 million . On May 4, 2017, the revolving credit facility was further amended to increase the borrowing base from $700.0 million to $1.0 billion , adjust certain of the Company’s investment baskets and add five additional banks to the syndicate. On November 21, 2017, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.5% and (b) add a provision that allows Gulfport to elect a commitment amount (the “Elected Commitment Amount”) that is less than the borrowing base. In connection with this amendment, the borrowing base was set at $1.2 billion , with an elected commitment of $1.0 billion . As of March 31, 2018 , $200.0 million was outstanding under the revolving credit facility and the total availability for future borrowings under this facility, after giving effect to an aggregate of $242.8 million of letters of credit, was $557.2 million . The Company’s wholly-owned subsidiaries have guaranteed the obligations of the Company under the revolving credit facility. Advances under the revolving credit facility may be in the form of either base rate loans or eurodollar loans. The interest rate for base rate loans is equal to (1) the applicable rate, which ranges from 0.50% to 1.50% , plus (2) the highest of: (a) the federal funds rate plus 0.50% , (b) the rate of interest in effect for such day as publicly announced from time to time by agent as its “prime rate,” and (c) the eurodollar rate for an interest period of one month plus 1.00% . The interest rate for eurodollar loans is equal to (1) the applicable rate, which ranges from 1.50% to 2.50% , plus (2) the London interbank offered rate that appears on pages LIBOR01 or LIBOR02 of the Reuters screen that displays such rate for deposits in U.S. dollars, or, if such rate is not available, the rate as administered by ICE Benchmark Administration (or any other person that takes over administration of such rate) per annum equal to the offered rate on such other page or service that displays on average London interbank offered rate as determined by ICE Benchmark Administration (or any other person that takes over administration of such rate) for deposits in U.S. dollars, or, if such rate is not available, the average quotations for three major New York money center banks of whom the agent shall inquire as the “London Interbank Offered Rate” for deposits in U.S. dollars. At March 31, 2018 , amounts borrowed under the credit facility bore interest at the eurodollar rate with a weighted average of 3.52% . The revolving credit facility contains customary negative covenants including, but not limited to, restrictions on the Company’s and its subsidiaries’ ability to: • incur indebtedness; • grant liens; • pay dividends and make other restricted payments; • make investments; • make fundamental changes; • enter into swap contracts; • dispose of assets; • change the nature of their business; and • enter into transactions with affiliates. The negative covenants are subject to certain exceptions as specified in the revolving credit facility. The revolving credit facility also contains certain affirmative covenants, including, but not limited to the following financial covenants: (i) the ratio of net funded debt to EBITDAX (net income, excluding (i) any non-cash revenue or expense associated with swap contracts resulting from ASC 815 and (ii) any cash or non-cash revenue or expense attributable to minority investments plus without duplication and, in the case of expenses, to the extent deducted from revenues in determining net income, the sum of (a) the aggregate amount of consolidated interest expense for such period, (b) the aggregate amount of income, franchise, capital or similar tax expense (other than ad valorem taxes) for such period, (c) all amounts attributable to depletion, depreciation, amortization and asset or goodwill impairment or writedown for such period, (d) all other non-cash charges, (e) exploration costs deducted in determining net income under successful efforts accounting, (f) actual cash distributions received from minority investments, (g) to the extent actually reimbursed by insurance, expenses with respect to liability on casualty events or business interruption, and (h) all reasonable transaction expenses related to dispositions and acquisitions of assets, investments and debt and equity offerings (provided that expenses related to any unsuccessful disposition will be limited to $3.0 million in the aggregate) for a twelve-month period may not be greater than 4.00 to 1.00 ; and (ii) the ratio of EBITDAX to interest expense for a twelve-month period may not be less than 3.00 to 1.00 . The Company was in compliance with its financial covenants at March 31, 2018 . In connection with the Company's 2018 spring redetermination under the revolving credit facility, the lead lenders have proposed to increase the Company's borrowing base from $1.2 billion to $1.4 billion , with an elected commitment of $1.0 billion , and decrease the interest rate by 25 basis points, subject to the approval of the additional required banks within the syndicate. (2) On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of 6.625% Senior Notes due 2023 (the “2023 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2023 Notes Offering”). The Company received net proceeds of approximately $343.6 million after initial purchaser discounts and commissions and estimated offering expenses. The 2023 Notes were issued under an indenture, dated as of April 21, 2015, among the Company, the subsidiary guarantors party thereto and Wells Fargo Bank, National Association, as trustee. In October 2015, the 2023 Notes were exchanged for a new issue of substantially identical debt securities registered under the Securities Act. Pursuant to the indenture relating to the 2023 Notes, interest on the 2023 Notes accrues at a rate of 6.625% per annum on the outstanding principal amount thereof, payable semi-annually on May 1 and November 1 of each year. The 2023 Notes are not guaranteed by Grizzly Holdings, Inc. and will not be guaranteed by any of the Company’s future unrestricted subsidiaries. (3) On October 14, 2016, the Company issued the 2024 Notes in aggregate principal amount of $650.0 million . The 2024 Notes were issued under an indenture, dated as of October 14, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2024 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2024 Notes Offering”). Under the 2024 Indenture, interest on the 2024 Notes accrues at a rate of 6.000% per annum on the outstanding principal amount thereof from October 14, 2016, payable semi-annually on April 15 and October 15 of each year, commencing on April 15, 2017. The 2024 Notes will mature on October 15, 2024. The Company received approximately $638.9 million in net proceeds from the offering of the 2024 Notes, which was used, together with cash on hand, to purchase the then outstanding 2020 Notes in a concurrent cash tender offer, to pay fees and expenses thereof, and to redeem any of the 2020 Notes that remained outstanding after the completion of the tender offer. (4) On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of 6.375% Senior Notes due 2025 (the “2025 Notes”). The 2025 Notes were issued under an indenture, dated as of December 21, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2025 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Under the 2025 Indenture, interest on the 2025 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from December 21, 2016, payable semi-annually on May 15 and November 15 of each year, commencing on May 15, 2017. The 2025 Notes will mature on May 15, 2025. The Company received approximately $584.7 million in net proceeds from the offering of the 2025 Notes, which was used, together with the net proceeds from the Company’s December 2016 common stock offering and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. See “Note 1 – Acquisitions” for additional discussion of the Vitruvian Acquisition. (5) On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of its 6.375% Senior Notes due 2026 (the “2026 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Interest on the 2026 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from October 11, 2017, payable semi-annually on January 15 and July 15 of each year, commencing on January 15, 2018. The 2026 Notes will mature on January 15, 2026. The Company received approximately $444.1 million in net proceeds from the offering of the 2026 Notes, a portion of which was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. (6) Loan issuance costs related to the 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes (collectively the “Notes”) have been presented as a reduction to the Notes. At March 31, 2018 , total unamortized debt issuance costs were $5.0 million for the 2023 Notes, $9.6 million for the 2024 Notes, $13.6 million for the 2025 Notes and $5.5 million for the 2026 Notes. In addition, loan commitment fee costs for the construction loan agreement described immediately below were $0.1 million at March 31, 2018 . (7) On June 4, 2015, the Company entered into a construction loan agreement (the “Construction Loan”) with InterBank for the construction of a new corporate headquarters in Oklahoma City, which was substantially completed in December 2016. The Construction Loan allows for maximum principal borrowings of $24.5 million and required the Company to fund 30% of the cost of the construction before any funds could be drawn, which occurred in January 2016. Interest accrues daily on the outstanding principal balance at a fixed rate of 4.50% per annum and was payable on the last day of the month through May 31, 2017. Starting June 30, 2017, the Company began making monthly payments of principal and interest, with the final payment due June 4, 2025. At March 31, 2018 , the total borrowings under the Construction Loan were approximately $23.6 million .

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Share-based Compensation [Abstract]
Summary of Restricted Stock Activity	The following table summarizes restricted stock activity for the three months ended March 31, 2018 : Number of Unvested Restricted Shares Weighted Average Grant Date Fair Value Unvested shares as of January 1, 2018 976,027 $ 18.71 Granted 140,041 8.77 Vested (109,933 ) 21.42 Forfeited (5,937 ) 17.34 Unvested shares as of March 31, 2018 1,000,198 $ 17.03

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Reconciliation of the Components of Basic and Diluted Net Income per Common Share	Reconciliations of the components of basic and diluted net income per common share are presented in the tables below: Three months ended March 31, 2018 2017 Income Shares Per Share Income Shares Per Share (In thousands, except share data) Basic: Net income $ 90,090 180,714,881 $ 0.50 $ 154,455 170,272,685 $ 0.91 Effect of dilutive securities: Stock options and awards — 87,420 — 215,834 Diluted: Net income $ 90,090 180,802,301 $ 0.50 $ 154,455 170,488,519 $ 0.91

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Long-term Purchase Commitment [Line Items]
Schedule of Future Minimum Lease Commitments	Future minimum lease commitments under these leases at March 31, 2018 were as follows: (In thousands) Remaining 2018 $ 80 2019 54 Total $ 134
Schedule of Firm Transportation Commitments	The table below presents these commitments at March 31, 2018 as follows: (MMBtu per day) Remaining 2018 552,000 2019 659,000 2020 526,000 2021 372,000 2022 272,000 Thereafter 240,000 Total 2,621,000
Transportation commitment
Long-term Purchase Commitment [Line Items]
Schedule of Other Commitments	The table below presents these commitments at March 31, 2018 as follows: (In thousands) Remaining 2018 $ 186,036 2019 251,644 2020 247,581 2021 246,620 2022 246,620 Thereafter 2,511,853 Total $ 3,690,354

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Schedule of Open Fixed Price Swap Positions	Below is a summary of the Company’s open fixed price swap positions as of March 31, 2018 . Location Daily Volume (MMBtu/day) Weighted Remaining 2018 NYMEX Henry Hub 927,000 $ 3.02 2019 NYMEX Henry Hub 647,000 $ 2.84 2020 NYMEX Henry Hub 45,000 $ 2.77 Location Daily Volume Weighted Remaining 2018 ARGUS LLS 2,000 $ 56.22 2019 ARGUS LLS 1,000 $ 59.55 Remaining 2018 NYMEX WTI 4,000 $ 53.99 2019 NYMEX WTI 3,000 $ 57.62 Location Daily Volume Weighted Remaining 2018 Mont Belvieu C3 4,000 $ 28.97 2019 Mont Belvieu C3 1,000 $ 27.05 Remaining 2018 Mont Belvieu C5 500 $ 46.62 The Company sold call options and used the associated premiums to enhance the fixed price for a portion of the fixed price natural gas swaps listed above. Each short call option has an established ceiling price. When the referenced settlement price is above the price ceiling established by these short call options, the Company pays its counterparty an amount equal to the difference between the referenced settlement price and the price ceiling multiplied by the hedged contract volumes. Location Daily Volume (MMBtu/day) Weighted Average Price April 2018 - March 2019 NYMEX Henry Hub 50,000 $ 3.13 April 2019 - December 2019 NYMEX Henry Hub 30,000 $ 3.10
Schedule of Derivative Instruments In Balance Sheet	The following table presents the fair value of the Company’s derivative instruments on a gross basis at March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (In thousands) Short-term derivative instruments - asset $ 50,906 $ 78,847 Long-term derivative instruments - asset $ 15,769 $ 8,685 Short-term derivative instruments - liability $ 37,570 $ 32,534 Long-term derivative instruments - liability $ 2,499 $ 2,989
Schedule of Net Gain (Loss) on Derivatives	The following table presents the gain and loss recognized in Net (loss) gain on natural gas, oil and NGL derivatives in the accompanying consolidated statements of operations for the three months ended March 31, 2018 and 2017 . Net (loss) gain on derivative instruments Three months ended March 31, 2018 2017 (In thousands) Natural gas derivatives $ (9,696 ) $ 86,277 Oil derivatives (9,147 ) 10,905 Natural gas liquids derivatives 2,314 2,395 Total $ (16,529 ) $ 99,577
Recognized Derivative Assets	The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of March 31, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 66,675 $ (27,431 ) $ 39,244 Derivative liabilities $ (40,069 ) $ 27,431 $ (12,638 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 )
Recognized Derivative Liabilities	The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of March 31, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 66,675 $ (27,431 ) $ 39,244 Derivative liabilities $ (40,069 ) $ 27,431 $ (12,638 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Financial and Non-Financial Assets and Liabilities by Valuation Level	The following tables summarize the Company’s financial and non-financial assets and liabilities by FASB ASC 820 valuation level as of March 31, 2018 and December 31, 2017 : March 31, 2018 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 66,675 $ — Liabilities: Derivative Instruments $ — $ 40,069 $ — December 31, 2017 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 87,532 $ — Liabilities: Derivative Instruments $ — $ 35,523 $ —

Condensed Consolidating Finan36

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2018
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Balance Sheets	The following condensed consolidating balance sheets, statements of operations, statements of comprehensive income (loss) and statements of cash flows are provided for the Parent, the Guarantors and the Non-Guarantor and include the consolidating adjustments and eliminations necessary to arrive at the information for the Company on a condensed consolidated basis. The information has been presented using the equity method of accounting for the Parent’s ownership of the Guarantors and the Non-Guarantor. CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 81,357 $ 37,254 $ 2 $ — $ 118,613 Accounts receivable - oil and natural gas 133,387 66,070 — — 199,457 Accounts receivable - intercompany 585,111 64,492 — (649,603 ) — Prepaid expenses and other current assets 6,115 1,449 — — 7,564 Short-term derivative instruments 50,906 — — — 50,906 Total current assets 856,876 169,265 2 (649,603 ) 376,540 Property and equipment: Oil and natural gas properties, full-cost accounting 6,769,164 2,702,262 — (729 ) 9,470,697 Other property and equipment 89,597 51 — — 89,648 Accumulated depletion, depreciation, amortization and impairment (4,264,609 ) (38 ) — — (4,264,647 ) Property and equipment, net 2,594,152 2,702,275 — (729 ) 5,295,698 Other assets: Equity investments and investments in subsidiaries 2,458,237 77,350 53,563 (2,277,456 ) 311,694 Long-term derivative instruments 15,769 — — — 15,769 Deferred tax asset — — — — — Inventories 6,045 2,460 — — 8,505 Other assets 13,569 6,617 — — 20,186 Total other assets 2,493,620 86,427 53,563 (2,277,456 ) 356,154 Total assets $ 5,944,648 $ 2,957,967 $ 53,565 $ (2,927,788 ) $ 6,028,392 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 443,963 $ 133,585 $ — $ — $ 577,548 Accounts payable - intercompany 64,980 584,495 128 (649,603 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 37,570 — — — 37,570 Current maturities of long-term debt 629 — — — 629 Total current liabilities 547,262 718,080 128 (649,603 ) 615,867 Long-term derivative instruments 2,499 — — — 2,499 Asset retirement obligation - long-term 64,091 12,176 — — 76,267 Deferred tax liability 2,884 — — — 2,884 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,239,023 — — — 2,239,023 Total liabilities 2,855,759 733,219 128 (649,603 ) 2,939,503 Stockholders’ equity: Common stock 1,735 — — — 1,735 Paid-in capital 4,319,034 1,915,598 260,877 (2,176,475 ) 4,319,034 Accumulated other comprehensive (loss) income (46,042 ) — (43,909 ) 43,909 (46,042 ) Retained (deficit) earnings (1,185,838 ) 309,150 (163,531 ) (145,619 ) (1,185,838 ) Total stockholders’ equity 3,088,889 2,224,748 53,437 (2,278,185 ) 3,088,889 Total liabilities and stockholders ’ equity $ 5,944,648 $ 2,957,967 $ 53,565 $ (2,927,788 ) $ 6,028,392 CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) December 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 67,908 $ 31,649 $ — $ — $ 99,557 Accounts receivable - oil and natural gas 128,121 54,092 — — 182,213 Accounts receivable - intercompany 554,439 63,374 — (617,813 ) — Prepaid expenses and other current assets 4,719 193 — — 4,912 Short-term derivative instruments 78,847 — — — 78,847 Total current assets 834,034 149,308 — (617,813 ) 365,529 Property and equipment: Oil and natural gas properties, full-cost accounting, 6,562,147 2,607,738 — (729 ) 9,169,156 Other property and equipment 86,711 43 — — 86,754 Accumulated depletion, depreciation, amortization and impairment (4,153,696 ) (37 ) — — (4,153,733 ) Property and equipment, net 2,495,162 2,607,744 — (729 ) 5,102,177 Other assets: Equity investments and investments in subsidiaries 2,361,575 77,744 57,641 (2,194,848 ) 302,112 Long-term derivative instruments 8,685 — — — 8,685 Deferred tax asset 1,208 — — — 1,208 Inventories 5,816 2,411 — — 8,227 Other assets 12,483 7,331 — — 19,814 Total other assets 2,389,767 87,486 57,641 (2,194,848 ) 340,046 Total assets $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 416,249 $ 137,361 $ — $ (1 ) $ 553,609 Accounts payable - intercompany 63,373 554,313 127 (617,813 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 32,534 — — — 32,534 Current maturities of long-term debt 622 — — — 622 Total current liabilities 512,898 691,674 127 (617,814 ) 586,885 Long-term derivative instruments 2,989 — — — 2,989 Asset retirement obligation - long-term 63,141 11,839 — — 74,980 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,038,321 — — — 2,038,321 Total liabilities 2,617,349 706,476 127 (617,814 ) 2,706,138 Stockholders’ equity: Common stock 1,831 — — — 1,831 Paid-in capital 4,416,250 1,915,598 259,307 (2,174,905 ) 4,416,250 Accumulated other comprehensive (loss) income (40,539 ) — (38,593 ) 38,593 (40,539 ) Retained (deficit) earnings (1,275,928 ) 222,464 (163,200 ) (59,264 ) (1,275,928 ) Total stockholders’ equity 3,101,614 2,138,062 57,514 (2,195,576 ) 3,101,614 Total liabilities and stockholders ’ equity $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752
Condensed Consolidating Statements of Operations	CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 213,561 $ 111,831 $ — $ — $ 325,392 Costs and expenses: Lease operating expenses 13,831 5,075 — — 18,906 Production taxes 4,011 2,843 — — 6,854 Midstream gathering and processing 45,666 18,527 — — 64,193 Depreciation, depletion and amortization 111,017 1 — — 111,018 General and administrative 13,811 (713 ) 1 — 13,099 Accretion expense 790 214 — — 1,004 Acquisition expense — — — — — 189,126 25,947 1 — 215,074 INCOME (LOSS) FROM OPERATIONS 24,435 85,884 (1 ) — 110,318 OTHER (INCOME) EXPENSE: Interest expense 34,393 (428 ) — — 33,965 Interest income (31 ) (6 ) — — (37 ) (Income) loss from equity method investments and investments in subsidiaries (99,864 ) (357 ) 330 86,355 (13,536 ) Other income (84 ) (11 ) — — (95 ) (65,586 ) (802 ) 330 86,355 20,297 INCOME (LOSS) BEFORE INCOME TAXES 90,021 86,686 (331 ) (86,355 ) 90,021 INCOME TAX BENEFIT (69 ) — — — (69 ) NET INCOME (LOSS) $ 90,090 $ 86,686 $ (331 ) $ (86,355 ) $ 90,090 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 272,441 $ 60,563 $ — $ — $ 333,004 Costs and expenses: Lease operating expenses 17,449 1,854 — — 19,303 Production taxes 3,102 804 — — 3,906 Midstream gathering and processing 37,724 10,217 — — 47,941 Depreciation, depletion and amortization 65,990 1 — — 65,991 General and administrative 12,874 (275 ) 1 — 12,600 Accretion expense 282 — — — 282 Acquisition expense — 1,298 — — 1,298 137,421 13,899 1 — 151,321 INCOME (LOSS) FROM OPERATIONS 135,020 46,664 (1 ) — 181,683 OTHER (INCOME) EXPENSE: Interest expense 25,048 (1,569 ) — — 23,479 Interest income (842 ) — — — (842 ) (Income) loss from equity method investments and investments in subsidiaries (42,614 ) 2,541 365 44,615 4,907 Other (income) expense (1,027 ) (189 ) — 900 (316 ) (19,435 ) 783 365 45,515 27,228 INCOME (LOSS) BEFORE INCOME TAXES 154,455 45,881 (366 ) (45,515 ) 154,455 INCOME TAX EXPENSE — — — — — NET INCOME (LOSS) $ 154,455 $ 45,881 $ (366 ) $ (45,515 ) $ 154,455
Condensed Consolidating Statements of Comprehensive Income (Loss)	CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 90,090 $ 86,686 $ (331 ) $ (86,355 ) $ 90,090 Foreign currency translation adjustment (5,503 ) (187 ) (5,316 ) 5,503 (5,503 ) Other comprehensive (loss) income (5,503 ) (187 ) (5,316 ) 5,503 (5,503 ) Comprehensive income (loss) $ 84,587 $ 86,499 $ (5,647 ) $ (80,852 ) $ 84,587 Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 154,455 $ 45,881 $ (366 ) $ (45,515 ) $ 154,455 Foreign currency translation adjustment 1,373 55 1,318 (1,373 ) 1,373 Other comprehensive income (loss) 1,373 55 1,318 (1,373 ) 1,373 Comprehensive income (loss) $ 155,828 $ 45,936 $ 952 $ (46,888 ) $ 155,828
Condensed Consolidating Statements of Cash Flows	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (Amounts in thousands) Three months ended March 31, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by operating activities $ 144,895 $ 81,452 $ 1 $ 1 $ 226,349 Net cash (used in) provided by investing activities (231,024 ) (75,847 ) (1,569 ) 1,569 (306,871 ) Net cash provided by (used in) financing activities 99,578 — 1,570 (1,570 ) 99,578 Net increase in cash, cash equivalents and restricted cash 13,449 5,605 2 — 19,056 Cash, cash equivalents and restricted cash at beginning of period 67,908 31,649 — — 99,557 Cash, cash equivalents and restricted cash at end of period $ 81,357 $ 37,254 $ 2 $ — $ 118,613 Three months ended March 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by operating activities $ 139,260 $ 3,384 $ 1 $ — $ 142,645 Net cash (used in) provided by investing activities (1,557,852 ) (1,348,964 ) (673 ) 1,374,810 (1,532,679 ) Net cash provided by (used in) financing activities 31,644 1,374,137 673 (1,374,810 ) 31,644 Net (decrease) increase in cash, cash equivalents and restricted cash (1,386,948 ) 28,557 1 — (1,358,390 ) Cash, cash equivalents and restricted cash at beginning of period 1,458,882 1,993 — — 1,460,875 Cash, cash equivalents and restricted cash at end of period $ 71,934 $ 30,550 $ 1 $ — $ 102,485

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) $ / shares in Units, shares in Millions	Feb. 17, 2017USD ($)a$ / sharesshares	Mar. 31, 2017USD ($)	Feb. 16, 2017USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 15, 2016$ / shares
Business Acquisition [Line Items]
Acquisition costs				$ 0	$ 1,298,000
Common stock share price (in usd per share) | $ / shares	$ 19.48					$ 20.96
Revenue		$ 26,200,000
Vitruvian acquisition
Business Acquisition [Line Items]
Net surface area (in acre) | a	46,400
Total initial purchase price	$ 1,850,000,000
Payments to acquire businesses	$ 1,354,093,000
Equity interest issued or issuable, number of shares (in shares) | shares	23.9
Acquisition costs				$ 0	$ 1,300,000
Goodwill	$ 0
Bargain purchase gain	$ 0
Initial purchase share price (in usd per share) | $ / shares						$ 20.96
Decrease in fair value of shares issued for acquisition, amount			$ 35,300,000
Vitruvian acquisition | Indemnity escrow
Business Acquisition [Line Items]
Equity interest issued or issuable, number of shares (in shares) | shares	5.2

Acquisitions (Allocation of Pur

Acquisitions (Allocation of Purchase Price) (Details) - Vitruvian acquisition $ in Thousands	Feb. 17, 2017USD ($)
Business Acquisition [Line Items]
Cash, net of purchase price adjustments	$ 1,354,093
Fair value of Gulfport’s common stock issued	464,639
Total consideration	1,818,732
Asset retirement obligations	(6,489)
Total fair value of net identifiable assets acquired	1,818,732
Proved properties
Business Acquisition [Line Items]
Oil and natural gas properties	362,264
Unproved properties
Business Acquisition [Line Items]
Oil and natural gas properties	$ 1,462,957

Acquisitions (Pro Forma) (Detai

Acquisitions (Pro Forma) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenue	$ 26,200
Vitruvian acquisition
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma revenue		$ 368,903
Pro forma net income		$ 175,881
Pro forma earnings per share (basic) (in usd per share)		$ 1.03
Pro forma earnings per share (diluted) (in usd per share)		$ 1.03

Property and Equipment (Schedul

Property and Equipment (Schedule of Property and Equipment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Oil and natural gas properties	$ 9,470,697	$ 9,169,156
Office furniture and fixtures	40,236	37,369
Building	44,592	44,565
Land	4,820	4,820
Total property and equipment	9,560,345	9,255,910
Accumulated depletion, depreciation, amortization and impairment	(4,264,647)	(4,153,733)
Property and equipment, net	$ 5,295,698	$ 5,102,177

Property and Equipment (Narrati

Property and Equipment (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)usd_per_mcf	Mar. 31, 2017USD ($)usd_per_mcf	Dec. 31, 2017USD ($)
Property, Plant and Equipment [Line Items]
Impairment of oil and natural gas properties	$ 0	$ 0
Cumulative capitalization of general and administrative costs incurred and capitalized to the full cost pool	174,400,000
Capitalized general and administrative costs	$ 8,800,000	$ 8,400,000
Depletion per Mcf of gas equivalent (usd per Mcfe) | usd_per_mcf	0.93	0.84
Capitalized costs of oil and natural gas properties excluded from amortization	$ 2,971,119,000		$ 2,912,974,000
Non-producing leases, extension term	5 years
Minimum
Property, Plant and Equipment [Line Items]
Expected number of years amortization will commence	3 years
Maximum
Property, Plant and Equipment [Line Items]
Expected number of years amortization will commence	5 years

Property and Equipment (Summary

Property and Equipment (Summary of Non-producing Properties Excluded from Amortization by Area) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	$ 2,971,119	$ 2,912,974
Utica
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	1,548,121
MidContinent
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	1,421,853
Niobrara
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	449
Southern Louisiana
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	552
Bakken
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	99
Other
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	$ 45

Property and Equipment (Sched43

Property and Equipment (Schedule of Asset Retirement Obligation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation, beginning of period	$ 75,100	$ 34,276
Liabilities incurred	329	6,779
Liabilities settled	(99)
Accretion expense	1,004	282
Revisions in estimated cash flows	53	0
Asset retirement obligation as of end of period	76,387	41,337
Less current portion	120	195	$ 120
Asset retirement obligation, long-term	$ 76,267	$ 41,142	$ 74,980

Equity Investments (Investments

Equity Investments (Investments Accounted for by the Equity Method) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity investments and investments in subsidiaries	$ 311,694		$ 302,112
(Income) loss from equity method investments	$ (13,536)	$ 4,907
Investment in Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	23.50%
Equity investments and investments in subsidiaries	$ 0		0
(Income) loss from equity method investments	$ (41)	(243)
Investment in Grizzly Oil Sands ULC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	24.9999%
Equity investments and investments in subsidiaries	$ 53,564		57,641
(Income) loss from equity method investments	$ 330	365
Investment in Timber Wolf Terminals LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	50.00%
Equity investments and investments in subsidiaries	$ 980		983
(Income) loss from equity method investments	$ 2	4
Investment in Windsor Midstream LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	22.50%
Equity investments and investments in subsidiaries	$ 30		30
(Income) loss from equity method investments	$ 0	(311)
Investment in Stingray Cementing LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%
Equity investments and investments in subsidiaries	$ 0
(Income) loss from equity method investments	$ 0	128
Investment in Blackhawk Midstream LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	48.50%
Equity investments and investments in subsidiaries	$ 0		0
(Income) loss from equity method investments	$ 0	0
Investment in Stingray Energy Services LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%
Equity investments and investments in subsidiaries	$ 0		0
(Income) loss from equity method investments	$ 0	197
Investment in Sturgeon Acquisitions LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%			25.00%
Equity investments and investments in subsidiaries	$ 0		0
(Income) loss from equity method investments	$ 0	68
Investment in Mammoth Energy Services, Inc.
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	25.10%
Equity investments and investments in subsidiaries	$ 179,770		$ 165,715
(Income) loss from equity method investments	$ (13,470)	2,158
Investment in Strike Force Midstream LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	25.00%		25.00%
Equity investments and investments in subsidiaries	$ 77,350		$ 77,743
(Income) loss from equity method investments	$ (357)	$ 2,541

Equity Investments (Equity Inve

Equity Investments (Equity Investments Balance Sheet Disclosure) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Current assets	$ 395,679	$ 415,032
Noncurrent assets	2,109,829	1,542,090
Current liabilities	285,521	261,086
Noncurrent liabilities	$ 87,259	$ 148,839

Equity Investments (Equity In46

Equity Investments (Equity Investment Income Statement Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Gross revenue	$ 511,133	$ 94,478
Net income (loss)	$ 64,452	$ (25,339)

Equity Investments (Narrative)

Equity Investments (Narrative) (Details) $ / shares in Units, a in Thousands, shares in Millions	Jun. 05, 2017USD ($)$ / sharesshares	Dec. 31, 2017USD ($)	Mar. 31, 2018USD ($)aproject	Mar. 31, 2017USD ($)	Dec. 31, 2014entity	Sep. 30, 2014a	Dec. 31, 2014USD ($)	Feb. 17, 2017$ / shares	Dec. 15, 2016$ / shares	Apr. 30, 2015bbl	Mar. 31, 2015	Jun. 30, 2014bbl
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments and investments in subsidiaries			$ 13,536,000	$ (4,907,000)
Distributions from equity method investments			750,000	631,000
Payments for equity method investments			1,569,000	10,673,000
Share price (in dollars per share) | $ / shares								$ 19.48	$ 20.96
Tatex Thailand III LLC
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments		$ 200,000
Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments and investments in subsidiaries			$ 41,000	243,000
Equity method investment, ownership interest, percent			23.50%
Grizzly Oil Sands ULC
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (acres) | a			830
Income (loss) from equity method investments and investments in subsidiaries			$ (330,000)	(365,000)
Number of oil sand projects | project			3
Production volume (in Bbls/day) | bbl										2,200		11,300
Other than temporary impairment loss			$ 0	0
Equity method investment, amount of cash calls, based on proportionate ownership interest			1,600,000
Equity method investments, increase (decrease) due to foreign currency translation adjustment			$ (5,300,000)	1,300,000
Equity method investment, ownership interest, percent			24.9999%
Windsor Midstream LLC
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments and investments in subsidiaries			$ 0	311,000
Distributions from equity method investments			$ 0	200,000
Equity method investment, ownership interest, percent			22.50%
Coronado Midstream LLC | Windsor Midstream LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership interest, percent											28.40%
Sturgeon Acquisitions LLC
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments and investments in subsidiaries			$ 0	(68,000)
Equity method investment, ownership interest, percent			0.00%		25.00%		25.00%
Payments for equity method investments							$ 20,700,000
Gain on sale of equity method investments	$ 12,500,000
Mammoth Energy Services LP
Schedule of Equity Method Investments [Line Items]
Equity method investments, increase (decrease) due to foreign currency translation adjustment			$ (200,000)	100,000
Equity method investment, ownership interest, percent			25.10%		30.50%		30.50%
Number of entities contributed for ownership interest | entity					4
Shares received from equity method investee in exchange for ownership interest (in shares) | shares	2
Share price (in dollars per share) | $ / shares	$ 18.50
Strike Force Midstream LLC
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments and investments in subsidiaries			$ 357,000	(2,541,000)
Distributions from equity method investments			$ 800,000	400,000
Equity method investment, ownership interest, percent		25.00%	25.00%
Payments for equity method investments				$ 10,000,000
Phu Horm Field | Apico Llc
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (acres) | a			180
Concession Acreage in Southeast Asia | Tatex Thailand III LLC
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (acres) | a						245
Apico Llc | Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage			8.50%
Strike Force Midstream LLC | Rice Energy Inc
Schedule of Equity Method Investments [Line Items]
Ownership percentage by parent		75.00%

Long-Term Debt (Break-Down of L

Long-Term Debt (Break-Down of Long-Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Oct. 11, 2017	Dec. 21, 2016	Oct. 14, 2016	Jun. 04, 2015	Apr. 21, 2015
Debt Instrument [Line Items]
Net unamortized debt issuance costs	$ (33,927)	$ (34,781)
Less: current maturities of long term debt	(629)	(622)
Long-term debt, net of current maturities	2,239,023	2,038,321
Construction loans
Debt Instrument [Line Items]
Net unamortized debt issuance costs	(100)
6.625% Senior Notes due 2023 | Senior notes
Debt Instrument [Line Items]
Long-term debt	350,000	350,000
Net unamortized debt issuance costs	$ (5,000)
Stated interest rate, percent	6.625%						6.625%
6.000% Senior Notes due 2024 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 650,000	650,000
Net unamortized debt issuance costs	$ (9,600)
Stated interest rate, percent	6.00%				6.00%
6.375% Senior Notes due 2025 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 600,000	600,000
Net unamortized debt issuance costs	$ (13,600)
Stated interest rate, percent	6.375%			6.375%
6.375% Senior Notes Due 2026 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 450,000	450,000
Net unamortized debt issuance costs	(5,500)
Stated interest rate, percent			6.375%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement
Debt Instrument [Line Items]
Long-term debt	200,000	0
InterBank | Revolving credit agreement | Construction loans
Debt Instrument [Line Items]
Stated interest rate, percent						4.50%
InterBank | Letter of credit | Construction loans
Debt Instrument [Line Items]
Long-term debt	$ 23,579	$ 23,724

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details)

Nov. 21, 2017

May 04, 2017USD ($)bank

Dec. 21, 2016USD ($)

Oct. 14, 2016USD ($)

Jan. 31, 2016

Mar. 31, 2018USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Oct. 11, 2017USD ($)

May 05, 2017USD ($)

Mar. 29, 2017USD ($)

Jun. 04, 2015USD ($)

Apr. 21, 2015USD ($)

Debt Instrument [Line Items]

Capitalized interest expense, undeveloped properties

$ 800,000

$ 3,100,000

Capitalized interest expense, building construction

843,000

3,122,000

Debt issuance costs, net

33,927,000

$ 34,781,000

Construction loans

Debt Instrument [Line Items]

Capitalized interest expense, building construction

0

$ 0

Debt issuance costs, net

$ 100,000

Amended and restated credit agreement | Maximum

Debt Instrument [Line Items]

Debt covenant ratio for future EBITDAX

4

Amended and restated credit agreement | Revolving credit agreement

Debt Instrument [Line Items]

Debt covenant ratio for EBITDAX

3

7.75% Senior Notes due 2020 | Senior notes

Debt Instrument [Line Items]

Stated interest rate, percent

7.75%

6.000% Senior Notes due 2024 | Senior notes

Debt Instrument [Line Items]

Long-term debt

$ 650,000,000

650,000,000

Stated interest rate, percent

6.00%

6.00%

Debt instrument, amount

$ 650,000,000

Proceeds from issuance of Senior Notes

$ 638,900,000

Debt issuance costs, net

$ 9,600,000

6.625% Senior Notes due 2023 | Senior notes

Debt Instrument [Line Items]

Long-term debt

$ 350,000,000

350,000,000

Stated interest rate, percent

6.625%

6.625%

Debt instrument, amount

$ 350,000,000

Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses

$ 343,600,000

Debt issuance costs, net

$ 5,000,000

6.375% Senior Notes due 2025 | Senior notes

Debt Instrument [Line Items]

Long-term debt

$ 600,000,000

600,000,000

Stated interest rate, percent

6.375%

6.375%

Debt instrument, amount

$ 600,000,000

Proceeds from issuance of Senior Notes

$ 584,700,000

Debt issuance costs, net

$ 13,600,000

6.375% Senior Notes Due 2026 | Senior notes

Debt Instrument [Line Items]

Long-term debt

450,000,000

450,000,000

Stated interest rate, percent

6.375%

Debt instrument, amount

$ 450,000,000

Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses

$ 444,100,000

Debt issuance costs, net

$ 5,500,000

Nova Scotia, Amegy, KeyBank | Revolving credit agreement

Debt Instrument [Line Items]

Credit facility interest rate at the eurodollar rate

3.52%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Minimum

Debt Instrument [Line Items]

Stated interest rate, percent

0.50%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Maximum

Debt Instrument [Line Items]

Stated interest rate, percent

1.50%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Federal funds rate

Debt Instrument [Line Items]

Basis spread, percent

0.50%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar

Debt Instrument [Line Items]

Basis spread, percent

1.00%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar | Minimum

Debt Instrument [Line Items]

Stated interest rate, percent

1.50%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar | Maximum

Debt Instrument [Line Items]

Stated interest rate, percent

2.50%

Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 1,500,000,000

Minimum acquisition payment limit

$ 50,000,000

Minimum disposition of property limit

$ 50,000,000

Borrowing base

$ 700,000,000

1,200,000,000

$ 1,000,000,000

Number of banks added to syndicate | bank

5

Increase (decrease) in interest rate

0.50%

Long-term debt

200,000,000

0

Remaining borrowing capacity

$ 557,200,000

Nova Scotia, Amegy, KeyBank | Letter of credit | Amended and restated credit agreement

Debt Instrument [Line Items]

Basis spread, percent

0.25%

Credit facility outstanding

$ 242,800,000

Line of credit facility, elected commitment

1,000,000,000

Disposition costs, maximum expenses allowed

3,000,000

InterBank | Revolving credit agreement | Construction loans

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 24,500,000

Stated interest rate, percent

4.50%

InterBank | Letter of credit | Construction loans

Debt Instrument [Line Items]

Required minimum down payment, percent

30.00%

Long-term debt

$ 23,579,000

$ 23,724,000

Scenario, Forecast | Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement

Debt Instrument [Line Items]

Borrowing base

$ 1,400,000,000

Common Stock and Changes in C50

Common Stock and Changes in Capitalization (Narrative) (Details) - USD ($)	Feb. 17, 2017	Mar. 31, 2018	Jan. 31, 2018
Class of Stock [Line Items]
Stock repurchase program, amount authorized to acquire			$ 100,000,000
Amount of shares repurchased		$ 99,997,000
Vitruvian acquisition
Class of Stock [Line Items]
Total initial purchase price	$ 1,850,000,000
Payments to acquire businesses	$ 1,354,093,000
Equity interest issued or issuable, number of shares (in shares)	23,900,000
Vitruvian acquisition | Indemnity escrow
Class of Stock [Line Items]
Equity interest issued or issuable, number of shares (in shares)	5,200,000
Common Stock
Class of Stock [Line Items]
Shares repurchased (in shares)		9,692,356
Amount of shares repurchased		$ 97,000

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation [Abstract]
Stock-based compensation cost	$ 2.7	$ 2.6
Capitalized stock-based compensation cost	1.1	$ 1
Unrecognized compensation expense	$ 12.9
Weighted average period of expense recognition period	1 year 6 months 11 days

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of Restricted Stock Award and Unit Activity) (Details) - Restricted Stock	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Number of Unvested Restricted Shares
Unvested shares as of January 1, 2018 (in shares) | shares	976,027
Granted (in shares) | shares	140,041
Vested (in shares) | shares	(109,933)
Forfeited (in shares) | shares	(5,937)
Unvested shares as of March 31, 2018 (in shares) | shares	1,000,198
Weighted Average Grant Date Fair Value
Unvested shares as of January 1, 2018 (in dollar per share) | $ / shares	$ 18.71
Granted (in dollars per share) | $ / shares	8.77
Vested (in dollars per share) | $ / shares	21.42
Forfeited (in dollars per share) | $ / shares	17.34
Unvested shares as of March 31, 2018 (in dollars per share) | $ / shares	$ 17.03

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share Reconciliation) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic:
Net income - basic	$ 90,090	$ 154,455
Net income - basic (in shares)	180,714,881	170,272,685
Net income - basic (in usd per share)	$ 0.50	$ 0.91
Effect of dilutive securities:
Stock options and awards	$ 0	$ 0
Stock options and awards (in shares)	87,420	215,834
Diluted:
Net income - diluted	$ 90,090	$ 154,455
Net income - diluted (in shares)	180,802,301	170,488,519
Net income (loss) - diluted (in usd per share)	$ 0.50	$ 0.91

Commitments and Contingencies54

Commitments and Contingencies (Narrative) (Details)	Jul. 29, 2016defendant	Feb. 09, 2016defendant	Mar. 11, 1997	Mar. 31, 2018USD ($)well	Mar. 31, 2017USD ($)	Jul. 29, 2016complaint	Dec. 31, 1997USD ($)well
Commitments [Line Items]
Plugging and abandonment trust on the WCBB properties				$ 3,100,000
Number of claims filed | complaint						2
Judicial District Court for the Parish of Cameron
Commitments [Line Items]
Number of defendants | defendant		26
Judicial District Court for the Parish of Vermillion
Commitments [Line Items]
Number of defendants | defendant	40
Loss on long-term purchase commitment | Muskie Proppant LLC
Commitments [Line Items]
Non-utilization fees, accrued damages year to date				$ 885,000	$ 0
Minimum
Commitments [Line Items]
Operating lease, term (in years)				1 year
WCBB
Commitments [Line Items]
Remaining interest in oil and gas property acquisition, percent							50.00%
Payments of seller's obligation to contribute							$ 18,000
Minimum number of wells to be plugged | well							20
Tenure of minimum wells to be plugged (in years)			20 years
Number of wells plugged | well				551
Purchase commitment
Commitments [Line Items]
Future minimum commitments				$ 26,200,000

Commitments and Contingencies55

Commitments and Contingencies (Operating Leases Future Minimum Lease Commitments) (Details) $ in Thousands	Mar. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remaining 2,018	$ 80
2,019	54
Total	$ 134

Commitments and Contingencies56

Commitments and Contingencies (Firm Transportation Commitments) (Details) $ in Thousands	Mar. 31, 2018USD ($)MMBTU
Other Commitments [Line Items]
Remaining 2018 | MMBTU	552,000
2019 | MMBTU	659,000
2020 | MMBTU	526,000
2021 | MMBTU	372,000
2022 | MMBTU	272,000
Thereafter | MMBTU	240,000
Total | MMBTU	2,621,000
Transportation commitment
Other Commitments [Line Items]
Remaining 2,018	$ 186,036
2,019	251,644
2,020	247,581
2,021	246,620
2,022	246,620
Thereafter	2,511,853
Total	3,690,354
Purchase commitment
Other Commitments [Line Items]
Remaining 2,018	$ 26,200

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Details) - 2019	3 Months Ended
	Mar. 31, 2018MMBTU$ / MMBTU
Derivative [Line Items]
Daily volume (in MMBtu) | MMBTU	100,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.05

Derivative Instruments (Schedul

Derivative Instruments (Schedule of Derivative Instruments) (Details)	Mar. 31, 2018MMBTU$ / bbl$ / MMBTUbbl
NYMEX Henry Hub Swap - 2018
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	927,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.02
NYMEX Henry Hub Swap - 2018 | Short | Call Option
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	50,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.13
NYMEX Henry Hub Swap - 2019
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	647,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	2.84
NYMEX Henry Hub Swap - 2019 | Short | Call Option
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	30,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.10
NYMEX Henry Hub Swap - 2020
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	45,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	2.77
ARGUS LLS Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	2,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	56.22
ARGUS LLS Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	59.55
NYMEX WTI Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	53.99
NYMEX WTI Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	3,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	57.62
Mont Belvieu C3 Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	28.97
Mont Belvieu C3 Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	27.05
Mont Belvieu C5 Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	500
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	46.62

Derivative Instruments (Sched59

Derivative Instruments (Schedule of Derivative Instruments in Statement of Financial Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Short-term derivative instruments - asset	$ 50,906	$ 78,847
Long-term derivative instruments - asset	15,769	8,685
Short-term derivative instruments - liability	37,570	32,534
Long-term derivative instruments - liability	$ 2,499	$ 2,989

Derivative Instruments (Net (Lo

Derivative Instruments (Net (Loss) Gain on Derivative Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	$ (16,529)	$ 99,577
Natural gas derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	(9,696)	86,277
Oil derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	(9,147)	10,905
Natural gas liquids derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	$ 2,314	$ 2,395

Derivative Instruments (Sched61

Derivative Instruments (Schedule of Offsetting) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Assets Presented in the Consolidated Balance Sheet	$ 66,675	$ 87,532
Gross Assets Subject to Mater Netting Agreement - assets	(27,431)	(22,199)
Net Amount - assets	39,244	65,333
Gross Liabilities Presented in the Consolidated Balance Sheet	(40,069)	(35,523)
Gross Amounts Subject to Master Netting Agreement - liabilities	27,431	22,199
Net Amount - liabilities	$ (12,638)	$ (13,324)

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Derivative Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Liabilities
Asset retirement obligation capitalized	$ 329	$ 6,779
Level 1
Assets
Derivative Instruments	0		$ 0
Liabilities
Derivative Instruments	0		0
Level 2
Assets
Derivative Instruments	66,675		87,532
Liabilities
Derivative Instruments	40,069		35,523
Level 3
Assets
Derivative Instruments	0		0
Liabilities
Derivative Instruments	0		$ 0
Asset retirement obligation capitalized	$ 400

Revenue from Contracts with C63

Revenue from Contracts with Customer (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Receivables from contracts with customers	$ 125.8	$ 135

Fair Value of Financial Instr64

Fair Value of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 33,927	$ 34,781
Senior notes | 6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Unamortized debt issuance costs	5,000
Senior notes | 6.000% Senior Notes due 2024
Debt Instrument [Line Items]
Unamortized debt issuance costs	9,600
Senior notes | 6.375% Senior Notes due 2025
Debt Instrument [Line Items]
Unamortized debt issuance costs	13,600
Senior notes | 6.375% Senior Notes Due 2026
Debt Instrument [Line Items]
Unamortized debt issuance costs	5,500
Carry value | Senior notes
Debt Instrument [Line Items]
Carrying value of notes	2,000,000
Fair value | Senior notes
Debt Instrument [Line Items]
Carrying value of notes	$ 2,000,000

Condensed Consolidating Finan65

Condensed Consolidating Financial Information (Narrative) (Details) - USD ($)	Mar. 31, 2018	Oct. 11, 2017	Dec. 21, 2016	Oct. 14, 2016	Apr. 21, 2015
6.625% Senior Notes due 2023 | Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount					$ 350,000,000
6.000% Senior Notes due 2024 | Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount				$ 650,000,000
6.375% Senior Notes due 2025 | Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount			$ 600,000,000
6.375% Senior Notes Due 2026 | Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount		$ 450,000,000
Guarantors
Condensed Financial Statements, Captions [Line Items]
Ownership percentage by parent	100.00%

Condensed Consolidating Finan66

Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 118,613	$ 99,557
Accounts receivable—oil and natural gas	199,457	182,213
Accounts receivable - intercompany		0
Prepaid expenses and other current assets	7,564	4,912
Short-term derivative instruments	50,906	78,847
Total current assets	376,540	365,529
Property and equipment:
Oil and natural gas properties	9,470,697	9,169,156
Other property and equipment	89,648	86,754
Accumulated depletion, depreciation, amortization and impairment	(4,264,647)	(4,153,733)
Property and equipment, net	5,295,698	5,102,177
Other assets
Equity investments and investments in subsidiaries	311,694	302,112
Long-term derivative instruments	15,769	8,685
Deferred tax asset	0	1,208
Inventories	8,505	8,227
Other assets	20,186	19,814
Total other assets	356,154	340,046
Total assets	6,028,392	5,807,752
Current liabilities:
Accounts payable and accrued liabilities	577,548	553,609
Accounts payable - intercompany	0	0
Asset retirement obligation—current	120	120	$ 195
Short-term derivative instruments	37,570	32,534
Current maturities of long-term debt	629	622
Total current liabilities	615,867	586,885
Long-term derivative instruments	2,499	2,989
Asset retirement obligation—long-term	76,267	74,980	41,142
Deferred tax liability	2,884	0
Other non-current liabilities	2,963	2,963
Long-term debt, net of current maturities	2,239,023	2,038,321
Total liabilities	2,939,503	2,706,138
Stockholders’ equity:
Common stock	1,735	1,831
Paid-in capital	4,319,034	4,416,250
Accumulated other comprehensive (loss) income	(46,042)	(40,539)
Retained (deficit) earnings	(1,185,838)	(1,275,928)
Total stockholders’ equity	3,088,889	3,101,614	$ 2,801,754	$ 2,183,892
Total liabilities and stockholders’ equity	6,028,392	5,807,752
Reportable Legal Entities | Parent
Current assets:
Cash and cash equivalents	81,357	67,908
Accounts receivable—oil and natural gas	133,387	128,121
Accounts receivable - intercompany	585,111	554,439
Prepaid expenses and other current assets	6,115	4,719
Short-term derivative instruments	50,906	78,847
Total current assets	856,876	834,034
Property and equipment:
Oil and natural gas properties	6,769,164	6,562,147
Other property and equipment	89,597	86,711
Accumulated depletion, depreciation, amortization and impairment	(4,264,609)	(4,153,696)
Property and equipment, net	2,594,152	2,495,162
Other assets
Equity investments and investments in subsidiaries	2,458,237	2,361,575
Long-term derivative instruments	15,769	8,685
Deferred tax asset	0	1,208
Inventories	6,045	5,816
Other assets	13,569	12,483
Total other assets	2,493,620	2,389,767
Total assets	5,944,648	5,718,963
Current liabilities:
Accounts payable and accrued liabilities	443,963	416,249
Accounts payable - intercompany	64,980	63,373
Asset retirement obligation—current	120	120
Short-term derivative instruments	37,570	32,534
Current maturities of long-term debt	629	622
Total current liabilities	547,262	512,898
Long-term derivative instruments	2,499	2,989
Asset retirement obligation—long-term	64,091	63,141
Deferred tax liability	2,884
Other non-current liabilities	0	0
Long-term debt, net of current maturities	2,239,023	2,038,321
Total liabilities	2,855,759	2,617,349
Stockholders’ equity:
Common stock	1,735	1,831
Paid-in capital	4,319,034	4,416,250
Accumulated other comprehensive (loss) income	(46,042)	(40,539)
Retained (deficit) earnings	(1,185,838)	(1,275,928)
Total stockholders’ equity	3,088,889	3,101,614
Total liabilities and stockholders’ equity	5,944,648	5,718,963
Reportable Legal Entities | Guarantors
Current assets:
Cash and cash equivalents	37,254	31,649
Accounts receivable—oil and natural gas	66,070	54,092
Accounts receivable - intercompany	64,492	63,374
Prepaid expenses and other current assets	1,449	193
Short-term derivative instruments	0	0
Total current assets	169,265	149,308
Property and equipment:
Oil and natural gas properties	2,702,262	2,607,738
Other property and equipment	51	43
Accumulated depletion, depreciation, amortization and impairment	(38)	(37)
Property and equipment, net	2,702,275	2,607,744
Other assets
Equity investments and investments in subsidiaries	77,350	77,744
Long-term derivative instruments	0	0
Deferred tax asset	0	0
Inventories	2,460	2,411
Other assets	6,617	7,331
Total other assets	86,427	87,486
Total assets	2,957,967	2,844,538
Current liabilities:
Accounts payable and accrued liabilities	133,585	137,361
Accounts payable - intercompany	584,495	554,313
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	718,080	691,674
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	12,176	11,839
Deferred tax liability	0
Other non-current liabilities	2,963	2,963
Long-term debt, net of current maturities	0	0
Total liabilities	733,219	706,476
Stockholders’ equity:
Common stock	0	0
Paid-in capital	1,915,598	1,915,598
Accumulated other comprehensive (loss) income	0	0
Retained (deficit) earnings	309,150	222,464
Total stockholders’ equity	2,224,748	2,138,062
Total liabilities and stockholders’ equity	2,957,967	2,844,538
Reportable Legal Entities | Non-Guarantor
Current assets:
Cash and cash equivalents	2	0
Accounts receivable—oil and natural gas	0	0
Accounts receivable - intercompany	0	0
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	2	0
Property and equipment:
Oil and natural gas properties	0	0
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	0	0
Other assets
Equity investments and investments in subsidiaries	53,563	57,641
Long-term derivative instruments	0	0
Deferred tax asset	0	0
Inventories	0	0
Other assets	0	0
Total other assets	53,563	57,641
Total assets	53,565	57,641
Current liabilities:
Accounts payable and accrued liabilities	0	0
Accounts payable - intercompany	128	127
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	128	127
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities	0	0
Long-term debt, net of current maturities	0	0
Total liabilities	128	127
Stockholders’ equity:
Common stock	0	0
Paid-in capital	260,877	259,307
Accumulated other comprehensive (loss) income	(43,909)	(38,593)
Retained (deficit) earnings	(163,531)	(163,200)
Total stockholders’ equity	53,437	57,514
Total liabilities and stockholders’ equity	53,565	57,641
Eliminations
Current assets:
Cash and cash equivalents	0	0
Accounts receivable—oil and natural gas	0	0
Accounts receivable - intercompany	(649,603)	(617,813)
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	(649,603)	(617,813)
Property and equipment:
Oil and natural gas properties	(729)	(729)
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	(729)	(729)
Other assets
Equity investments and investments in subsidiaries	(2,277,456)	(2,194,848)
Long-term derivative instruments	0	0
Deferred tax asset	0	0
Inventories	0	0
Other assets	0	0
Total other assets	(2,277,456)	(2,194,848)
Total assets	(2,927,788)	(2,813,390)
Current liabilities:
Accounts payable and accrued liabilities	0	(1)
Accounts payable - intercompany	(649,603)	(617,813)
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	(649,603)	(617,814)
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities	0	0
Long-term debt, net of current maturities	0	0
Total liabilities	(649,603)	(617,814)
Stockholders’ equity:
Common stock	0	0
Paid-in capital	(2,176,475)	(2,174,905)
Accumulated other comprehensive (loss) income	43,909	38,593
Retained (deficit) earnings	(145,619)	(59,264)
Total stockholders’ equity	(2,278,185)	(2,195,576)
Total liabilities and stockholders’ equity	$ (2,927,788)	$ (2,813,390)

Condensed Consolidating Finan67

Condensed Consolidating Financial Information (Condensed Consolidating Statements of Operations) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Total revenues	$ 325,392,000	$ 333,004,000
Costs and expenses:
Lease operating expenses	18,906,000	19,303,000
Production taxes	6,854,000	3,906,000
Midstream gathering and processing	64,193,000	47,941,000
Depreciation, depletion and amortization	111,018,000	65,991,000
Impairment of oil and natural gas properties	0	0
General and administrative	13,099,000	12,600,000
Accretion expense	1,004,000	282,000
Acquisition expense	0	1,298,000
Total costs and expenses	215,074,000	151,321,000
INCOME (LOSS) FROM OPERATIONS	110,318,000	181,683,000
OTHER (INCOME) EXPENSE:
Interest expense	33,965,000	23,479,000
Interest income	(37,000)	(842,000)
(Income) loss from equity method investments and investments in subsidiaries	(13,536,000)	4,907,000
Other (income) expense	(95,000)	(316,000)
Total other (income) expense	20,297,000	27,228,000
INCOME (LOSS) BEFORE INCOME TAXES	90,021,000	154,455,000
INCOME TAX BENEFIT	(69,000)	0
NET INCOME (LOSS)	90,090,000	154,455,000
Reportable Legal Entities | Parent
Revenues:
Total revenues	213,561,000	272,441,000
Costs and expenses:
Lease operating expenses	13,831,000	17,449,000
Production taxes	4,011,000	3,102,000
Midstream gathering and processing	45,666,000	37,724,000
Depreciation, depletion and amortization	111,017,000	65,990,000
General and administrative	13,811,000	12,874,000
Accretion expense	790,000	282,000
Acquisition expense	0	0
Total costs and expenses	189,126,000	137,421,000
INCOME (LOSS) FROM OPERATIONS	24,435,000	135,020,000
OTHER (INCOME) EXPENSE:
Interest expense	34,393,000	25,048,000
Interest income	(31,000)	(842,000)
(Income) loss from equity method investments and investments in subsidiaries	(99,864,000)	(42,614,000)
Other (income) expense	(84,000)	(1,027,000)
Total other (income) expense	(65,586,000)	(19,435,000)
INCOME (LOSS) BEFORE INCOME TAXES	90,021,000	154,455,000
INCOME TAX BENEFIT	(69,000)	0
NET INCOME (LOSS)	90,090,000	154,455,000
Reportable Legal Entities | Guarantors
Revenues:
Total revenues	111,831,000	60,563,000
Costs and expenses:
Lease operating expenses	5,075,000	1,854,000
Production taxes	2,843,000	804,000
Midstream gathering and processing	18,527,000	10,217,000
Depreciation, depletion and amortization	1,000	1,000
General and administrative	(713,000)	(275,000)
Accretion expense	214,000	0
Acquisition expense	0	1,298,000
Total costs and expenses	25,947,000	13,899,000
INCOME (LOSS) FROM OPERATIONS	85,884,000	46,664,000
OTHER (INCOME) EXPENSE:
Interest expense	(428,000)	(1,569,000)
Interest income	(6,000)	0
(Income) loss from equity method investments and investments in subsidiaries	(357,000)	2,541,000
Other (income) expense	(11,000)	(189,000)
Total other (income) expense	(802,000)	783,000
INCOME (LOSS) BEFORE INCOME TAXES	86,686,000	45,881,000
INCOME TAX BENEFIT	0	0
NET INCOME (LOSS)	86,686,000	45,881,000
Reportable Legal Entities | Non-Guarantor
Revenues:
Total revenues	0	0
Costs and expenses:
Lease operating expenses	0	0
Production taxes	0	0
Midstream gathering and processing	0	0
Depreciation, depletion and amortization	0	0
General and administrative	1,000	1,000
Accretion expense	0	0
Acquisition expense	0	0
Total costs and expenses	1,000	1,000
INCOME (LOSS) FROM OPERATIONS	(1,000)	(1,000)
OTHER (INCOME) EXPENSE:
Interest expense	0	0
Interest income	0	0
(Income) loss from equity method investments and investments in subsidiaries	330,000	365,000
Other (income) expense	0	0
Total other (income) expense	330,000	365,000
INCOME (LOSS) BEFORE INCOME TAXES	(331,000)	(366,000)
INCOME TAX BENEFIT	0	0
NET INCOME (LOSS)	(331,000)	(366,000)
Eliminations
Revenues:
Total revenues	0	0
Costs and expenses:
Lease operating expenses	0	0
Production taxes	0	0
Midstream gathering and processing	0	0
Depreciation, depletion and amortization	0	0
General and administrative	0	0
Accretion expense	0	0
Acquisition expense	0	0
Total costs and expenses	0	0
INCOME (LOSS) FROM OPERATIONS	0	0
OTHER (INCOME) EXPENSE:
Interest expense	0	0
Interest income	0	0
(Income) loss from equity method investments and investments in subsidiaries	86,355,000	44,615,000
Other (income) expense	0	900,000
Total other (income) expense	86,355,000	45,515,000
INCOME (LOSS) BEFORE INCOME TAXES	(86,355,000)	(45,515,000)
INCOME TAX BENEFIT	0	0
NET INCOME (LOSS)	$ (86,355,000)	$ (45,515,000)

Condensed Consolidating Finan68

Condensed Consolidating Financial Information (Condensed Consolidating Statements of Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 90,090	$ 154,455
Foreign currency translation adjustment	(5,503)	1,373
Other comprehensive (loss) income	(5,503)	1,373
Comprehensive income	84,587	155,828
Reportable Legal Entities | Parent
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	90,090	154,455
Foreign currency translation adjustment	(5,503)	1,373
Other comprehensive (loss) income	(5,503)	1,373
Comprehensive income	84,587	155,828
Reportable Legal Entities | Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	86,686	45,881
Foreign currency translation adjustment	(187)	55
Other comprehensive (loss) income	(187)	55
Comprehensive income	86,499	45,936
Reportable Legal Entities | Non-Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(331)	(366)
Foreign currency translation adjustment	(5,316)	1,318
Other comprehensive (loss) income	(5,316)	1,318
Comprehensive income	(5,647)	952
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(86,355)	(45,515)
Foreign currency translation adjustment	5,503	(1,373)
Other comprehensive (loss) income	5,503	(1,373)
Comprehensive income	$ (80,852)	$ (46,888)

Condensed Consolidating Finan69

Condensed Consolidating Financial Information (Condensed Consolidating Statements of Cash Flows (Details)) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 226,349	$ 142,645
Net cash (used in) provided by investing activities	(306,871)	(1,532,679)
Net cash provided by (used in) financing activities	99,578	31,644
Net increase (decrease) in cash, cash equivalents and restricted cash	19,056	(1,358,390)
Cash, cash equivalents and restricted cash at beginning of period	99,557	1,460,875
Cash, cash equivalents and restricted cash at end of period	118,613	102,485
Reportable Legal Entities | Parent
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	144,895	139,260
Net cash (used in) provided by investing activities	(231,024)	(1,557,852)
Net cash provided by (used in) financing activities	99,578	31,644
Net increase (decrease) in cash, cash equivalents and restricted cash	13,449	(1,386,948)
Cash, cash equivalents and restricted cash at beginning of period	67,908	1,458,882
Cash, cash equivalents and restricted cash at end of period	81,357	71,934
Reportable Legal Entities | Guarantors
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	81,452	3,384
Net cash (used in) provided by investing activities	(75,847)	(1,348,964)
Net cash provided by (used in) financing activities	0	1,374,137
Net increase (decrease) in cash, cash equivalents and restricted cash	5,605	28,557
Cash, cash equivalents and restricted cash at beginning of period	31,649	1,993
Cash, cash equivalents and restricted cash at end of period	37,254	30,550
Reportable Legal Entities | Non-Guarantor
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	1	1
Net cash (used in) provided by investing activities	(1,569)	(673)
Net cash provided by (used in) financing activities	1,570	673
Net increase (decrease) in cash, cash equivalents and restricted cash	2	1
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	2	1
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	1	0
Net cash (used in) provided by investing activities	1,569	1,374,810
Net cash provided by (used in) financing activities	(1,570)	(1,374,810)
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	$ 0	$ 0

Recent Accounting Pronounceme70

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to net cash used in investing activities	$ (306,871)	$ (1,532,679)
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in restricted cash			$ 185,000
Increase to net cash used in investing activities		$ 185,000

Subsequent Events (Details)

Subsequent Events (Details)	Apr. 26, 2018USD ($)	Mar. 31, 2018MMBTU$ / bbl$ / MMBTUbbl	Apr. 30, 2018MMBTU$ / bbl$ / MMBTUbbl	Mar. 31, 2018USD ($)$ / bbl$ / MMBTU	Mar. 31, 2017USD ($)	May 31, 2018USD ($)	Jan. 31, 2018USD ($)	Dec. 31, 2017
Subsequent Event [Line Items]
Payments for equity method investments | $				$ 1,569,000	$ 10,673,000
Stock repurchase program, amount authorized to acquire | $							$ 100,000,000
Strike Force Midstream LLC
Subsequent Event [Line Items]
Equity method investment, ownership interest, percent		25.00%		25.00%				25.00%
Payments for equity method investments | $					$ 10,000,000
NYMEX Henry Hub Swap - 2018
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU		927,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU		3.02		3.02
NYMEX Henry Hub Swap - 2019
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU		647,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU		2.84		2.84
NYMEX WTI Swap - 2019
Subsequent Event [Line Items]
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl		57.62		57.62
Daily volume (in Bbls) | bbl		3,000
Mont Belvieu C3 Swap - 2019
Subsequent Event [Line Items]
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl		27.05		27.05
Daily volume (in Bbls) | bbl		1,000
NYMEX Henry Hub Swap - 2020
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU		45,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU		2.77		2.77
Subsequent event | Strike Force Midstream LLC
Subsequent Event [Line Items]
Payments for equity method investments | $	$ 175,000,000
Subsequent event | NYMEX Henry Hub Swap - 2018
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU			53,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU			2.84
Subsequent event | NYMEX Henry Hub Swap - 2019
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU			15,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU			2.76
Subsequent event | NYMEX WTI Swap - 2019
Subsequent Event [Line Items]
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl			60.24
Daily volume (in Bbls) | bbl			1,000
Subsequent event | Mont Belvieu C3 Swap - 2019
Subsequent Event [Line Items]
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl			28.04
Daily volume (in Bbls) | bbl			2,000
Subsequent event | Mont Belvieu C5 Swap - 2019
Subsequent Event [Line Items]
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl			54.08
Daily volume (in Bbls) | bbl			500
Subsequent event | NYMEX Henry Hub Swap - 2020
Subsequent Event [Line Items]
Daily volume (in MMBtu) | MMBTU			5,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU			2.76
Minimum | Subsequent event
Subsequent Event [Line Items]
Stock repurchase program, amount authorized to acquire | $						$ 100,000,000
Maximum | Subsequent event
Subsequent Event [Line Items]
Stock repurchase program, amount authorized to acquire | $						$ 200,000,000