SM Energy (SM) 10-Q 29 Apr 20 2020 Q1 Quarterly report Financial data

Cover page

Cover page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 22, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-31539
Entity Registrant Name	SM ENERGY CO
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-0518430
Entity Address, Address Line One	1775 Sherman Street, Suite 1200,
Entity Address, City or Town	Denver,
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80203
City Area Code	(303)
Local Phone Number	861-8140
Title of 12(b) Security	Common stock, $0.01 par value
Trading Symbol	SM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		112,988,682
Entity Central Index Key	0000893538
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (in thousands, except share data) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 15	$ 10
Accounts receivable	143,311	184,732
Derivative assets	463,992	55,184
Prepaid expenses and other	17,842	12,708
Total current assets	625,160	252,634
Property and equipment (successful efforts method):
Proved oil and gas properties	8,043,156	8,934,020
Accumulated depletion, depreciation, and amortization	(4,389,103)	(4,177,876)
Unproved oil and gas properties	972,844	1,005,887
Wells in progress	224,509	118,769
Other property and equipment, net of accumulated depreciation of $64,815 and $64,032, respectively	36,932	72,848
Total property and equipment, net	4,888,338	5,953,648
Noncurrent assets:
Derivative assets	44,909	20,624
Other noncurrent assets	56,618	65,326
Total noncurrent assets	101,527	85,950
Total assets	5,615,025	6,292,232
Other property and equipment, accumulated depreciation	64,815	64,032
Current liabilities:
Accounts payable and accrued expenses	359,406	402,008
Derivative liabilities	8,277	50,846
Other current liabilities	15,780	19,189
Total current liabilities	383,463	472,043
Noncurrent liabilities:
Revolving credit facility	72,000	122,500
Senior Notes, net of unamortized deferred financing costs	2,413,663	2,453,035
Senior Convertible Notes, net of unamortized discount and deferred financing costs	159,721	157,263
Asset retirement obligations	85,267	84,134
Deferred income taxes	93,918	189,386
Derivative liabilities	7,202	3,444
Other noncurrent liabilities	58,074	61,433
Total noncurrent liabilities	2,889,845	3,071,195
Commitments and contingencies (note 6)
Stockholders’ equity:
Common stock, $0.01 par value - authorized: 200,000,000 shares; issued and outstanding: 112,988,682 and 112,987,952 shares, respectively	1,130	1,130
Additional paid-in capital	1,797,154	1,791,596
Retained earnings	554,562	967,587
Accumulated other comprehensive loss	(11,129)	(11,319)
Total stockholders' equity	2,341,717	2,748,994
Total liabilities and stockholders’ equity	$ 5,615,025	$ 6,292,232
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	112,988,682	112,987,952
Common Stock, Shares, Outstanding	112,988,682	112,987,952

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (in thousands, except per share data) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating revenues and other income:
Oil, gas, and NGL production revenue	$ 354,233	$ 340,476
Net gain on divestiture activity	0	61
Other operating revenues	1,501	393
Total operating revenues and other income	355,734	340,930
Operating expenses:
Oil, gas, and NGL production expense	119,552	121,305
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	233,489	177,746
Exploration	11,349	11,348
Impairment	989,763	6,338
General and administrative	27,447	32,086
Net derivative (gain) loss	(545,340)	177,081
Other operating expenses, net	566	335
Total operating expenses	836,826	526,239
Loss from operations	(481,092)	(185,309)
Interest expense	(41,512)	(37,980)
Gain on extinguishment of debt	12,195	0
Other non-operating expense, net	(494)	(317)
Loss before income taxes	(510,903)	(223,606)
Income tax benefit	99,008	46,038
Net loss	$ (411,895)	$ (177,568)
Basic weighted-average common shares outstanding	113,009	112,252
Diluted weighted-average common shares outstanding	113,009	112,252
Basic net loss per common share	$ (3.64)	$ (1.58)
Diluted net loss per common share	(3.64)	(1.58)
Dividends per common share	$ 0.01	$ 0.05

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED) (in thousands) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (411,895)	$ (177,568)
Other comprehensive income, net of tax:
Pension liability adjustment	190	263
Total other comprehensive income, net of tax	190	263
Total comprehensive loss	$ (411,705)	$ (177,305)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (UNAUDITED) (in thousands, except share data and dividends per share) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Cash dividends declared per share	$ 0.05
Balances, Common Stock, Shares, Outstanding, Beginning at Dec. 31, 2018		112,241,966
Balances, Total Stockholders' Equity, Beginning at Dec. 31, 2018	$ 2,920,322	$ 1,122	$ 1,765,738	$ 1,165,842	$ (12,380)
Increase (Decrease) in Stockholders' Equity
Net loss	(177,568)			(177,568)
Other comprehensive income	263				263
Cash dividends declared, per share	(5,612)			(5,612)
Issuance of common stock upon vesting of RSUs, net of shares used for tax withholdings (Shares)		2,579
Issuance of common stock upon vesting of RSUs, net of shares used for tax withholdings (Amount)	(18)	$ 0	(18)
Stock-based compensation expense	5,838		5,838
Balances, Common Stock, Shares, Outstanding, Ending at Mar. 31, 2019		112,244,545
Balances, Total Stockholders' Equity, Ending at Mar. 31, 2019	$ 2,743,225	$ 1,122	1,771,558	982,662	(12,117)
Cash dividends declared per share	$ 0.01
Balances, Common Stock, Shares, Outstanding, Beginning at Dec. 31, 2019	112,987,952	112,987,952
Balances, Total Stockholders' Equity, Beginning at Dec. 31, 2019	$ 2,748,994	$ 1,130	1,791,596	967,587	(11,319)
Increase (Decrease) in Stockholders' Equity
Net loss	(411,895)			(411,895)
Other comprehensive income	190				190
Cash dividends declared, per share	(1,130)			(1,130)
Issuance of common stock upon vesting of RSUs, net of shares used for tax withholdings (Shares)		730
Issuance of common stock upon vesting of RSUs, net of shares used for tax withholdings (Amount)	(3)	$ 0	(3)
Stock-based compensation expense	$ 5,561		5,561
Balances, Common Stock, Shares, Outstanding, Ending at Mar. 31, 2020	112,988,682	112,988,682
Balances, Total Stockholders' Equity, Ending at Mar. 31, 2020	$ 2,341,717	$ 1,130	$ 1,797,154	$ 554,562	$ (11,129)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (in thousands) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (411,895)	$ (177,568)
Adjustments to reconcile net loss to net cash provided by operating activities:
Net gain on divestiture activity	0	(61)
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	233,489	177,746
Impairment	989,763	6,338
Stock-based compensation expense	5,561	5,838
Net derivative (gain) loss	(545,340)	177,081
Derivative settlement gain (loss)	73,437	(4,969)
Amortization of debt discount and deferred financing costs	3,992	3,789
Gain on extinguishment of debt	(12,195)	0
Deferred income taxes	(99,347)	(47,003)
Other, net	(816)	(2,530)
Net change in working capital	(18,517)	(20,159)
Net cash provided by operating activities	218,132	118,502
Cash flows from investing activities:
Net proceeds from the sale of oil and gas properties	0	6,114
Capital expenditures	(139,306)	(249,340)
Other, net	0	291
Net cash used in investing activities	(139,306)	(242,935)
Cash flows from financing activities:
Proceeds from revolving credit facility	425,500	172,000
Repayment of revolving credit facility	(476,000)	(125,500)
Cash paid to repurchase 6.125% Senior Notes due 2022	(28,318)	0
Other, net	(3)	(18)
Net cash provided by (used in) financing activities	(78,821)	46,482
Net change in cash, cash equivalents, and restricted cash	5	(77,951)
Cash, cash equivalents, and restricted cash at beginning of period	10	77,965
Cash, cash equivalents, and restricted cash at end of period	15	14
Supplemental Cash Flow Information - Operating activities:
Cash paid for interest, net of capitalized interest	(47,469)	(39,957)
Supplemental Cash Flow Information - Investing activities:
Changes in capital expenditure accruals and other	16,802	62,185
Supplemental Cash Flow Information - Supplemental non-cash investing activities:
Carrying value of properties exchanged	$ 0	$ 65,788

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1 - Summary of Significant Accounting Policies Description of Operations SM Energy Company, together with its consolidated subsidiaries (“SM Energy” or the “Company”), is an independent energy company engaged in the acquisition, exploration, development, and production of oil, gas, and NGLs in the State of Texas. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information, the instructions to Quarterly Report on Form 10-Q, and Regulation S-X. These financial statements do not include all information and notes required by GAAP for annual financial statements. However, except as disclosed herein, there has been no material change in the information disclosed in the notes to the consolidated financial statements included in the 2019 Form 10-K. In the opinion of management, all adjustments, consisting of normal recurring adjustments considered necessary for a fair presentation of interim financial information, have been included. Operating results for the periods presented are not necessarily indicative of expected results for the full year. In connection with the preparation of the Company’s unaudited condensed consolidated financial statements, the Company evaluated events subsequent to the balance sheet date of March 31, 2020 , and through the filing of this report. Additionally, certain prior period amounts have been reclassified to conform to current period presentation in the accompanying unaudited condensed consolidated financial statements. Significant Accounting Policies The significant accounting policies followed by the Company are set forth in Note 1 - Summary of Significant Accounting Policies in the 2019 Form 10-K and are supplemented by the notes to the unaudited condensed consolidated financial statements included in this report. These unaudited condensed consolidated financial statements should be read in conjunction with the 2019 Form 10-K. Recently Issued Accounting Standards In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 was issued to reduce the complexity of accounting for income taxes for those entities that fall within the scope of the accounting standard. The guidance is to be applied using a prospective method, excluding amendments related to franchise taxes, which should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company early adopted ASU 2019-12 on January 1, 2020, and there was no material impact on the Company’s unaudited condensed consolidated financial statements or disclosures upon adoption. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”). ASU 2020-04 was issued to provide optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. Generally, the guidance is to be applied as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. ASU 2020-04 is effective for all entities as of March 12, 2020 through December 31, 2022. The Company is evaluating the options provided by ASU 2020-04. Please refer to Note 5 - Long-Term Debt for discussion of the use of the London Interbank Offered Rate (“LIBOR”) in connection with borrowings under the Credit Agreement. As disclosed in the 2019 Form 10-K, the Company adopted ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract on January 1, 2020. As expected, there was no material impact on the Company’s unaudited condensed consolidated financial statements or disclosures upon adoption of these ASUs. There are no ASUs that would have a material effect on the Company’s unaudited condensed consolidated financial statements and related disclosures that have been issued but not yet adopted by the Company as of March 31, 2020 , and through the filing of this report.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Note 2 - Revenue from Contracts with Customers The Company recognizes its share of revenue from the sale of produced oil, gas, and NGLs from its Midland Basin and South Texas assets. Oil, gas, and NGL production revenue presented within the accompanying unaudited condensed consolidated statements of operations (“accompanying statements of operations”) is reflective of the revenue generated from contracts with customers. The table below presents oil, gas, and NGL production revenue by product type for each of the Company’s operating regions for the three months ended March 31, 2020 , and 2019 : Midland Basin South Texas Total Three Months Ended March 31, Three Months Ended March 31, Three Months Ended March 31, 2020 2019 2020 2019 2020 2019 (in thousands) Oil production revenue $ 276,136 $ 225,247 $ 15,557 $ 13,814 $ 291,693 $ 239,061 Gas production revenue 11,334 15,592 29,376 49,521 40,710 65,113 NGL production revenue 58 21 21,772 36,281 21,830 36,302 Total $ 287,528 $ 240,860 $ 66,705 $ 99,616 $ 354,233 $ 340,476 Relative percentage 81 % 71 % 19 % 29 % 100 % 100 % ____________________________________________ Note: Amounts may not calculate due to rounding. The Company recognizes oil, gas, and NGL production revenue at the point in time when custody and title (“control”) of the product transfers to the purchaser, which differs depending on the applicable contractual terms. Transfer of control drives the presentation of transportation, gathering, processing, and other post-production expenses (“fees and other deductions”) within the accompanying statements of operations. Fees and other deductions incurred by the Company prior to control transfer are recorded within the oil, gas, and NGL production expense line item on the accompanying statements of operations. When control is transferred at or near the wellhead, sales are based on a wellhead market price that is impacted by fees and other deductions incurred by the purchaser subsequent to the transfer of control. Please refer to Note 2 - Revenue from Contracts with Customers in the 2019 Form 10-K for more information regarding the types of contracts under which oil, gas, and NGL production revenue is generated. Significant judgments made in applying the guidance in Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers, relate to the point in time when control transfers to purchasers in gas processing arrangements with midstream processors. The Company does not believe that significant judgments are required with respect to the determination of the transaction price, including amounts that represent variable consideration, as volume and price carry a low level of estimation uncertainty given the precision of volumetric measurements and the use of index pricing with generally predictable differentials. Accordingly, the Company does not consider estimates of variable consideration to be constrained. The Company’s performance obligations arise upon the production of hydrocarbons from wells in which the Company has an ownership interest. The performance obligations are considered satisfied upon control transferring to a purchaser at the wellhead, inlet, or tailgate of the midstream processor’s processing facility, or other contractually specified delivery point. The time period between production and satisfaction of performance obligations is generally less than one day; thus, there are no material unsatisfied or partially unsatisfied performance obligations at the end of the reporting period. Revenue is recorded in the month when performance obligations are satisfied. However, settlement statements from the purchasers of hydrocarbons and the related cash consideration are received 30 to 90 days after production has occurred. As a result, the Company must estimate the amount of production delivered to the customer and the consideration that will ultimately be received for sale of the product. Estimated revenue due to the Company is recorded within the accounts receivable line item on the accompanying unaudited condensed consolidated balance sheets (“accompanying balance sheets”) until payment is received. The accounts receivable balances from contracts with customers within the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , were $62.0 million and $146.3 million , respectively. To estimate accounts receivable from contracts with customers, the Company uses knowledge of its properties, historical performance, contractual arrangements, index pricing, quality and transportation differentials, and other factors as the basis for these estimates. Differences between estimates and actual amounts received for product sales are recorded in the month that payment is received from the purchaser.

Divestitures, Assets Held for S

Divestitures, Assets Held for Sale, and Acquisitions	3 Months Ended
	Mar. 31, 2020
Divestitures, Assets Held for Sale, and Acquisitions [Abstract]
Divestitures, Assets Held for Sale, and Acquisitions	Note 3 - Divestitures, Assets Held for Sale, and Acquisitions Divestitures No material divestitures occurred during the first quarters of 2020 and 2019 , and there were no assets classified as held for sale as of March 31, 2020 , or December 31, 2019 . Acquisitions No material acquisitions or acreage trades of oil and gas properties occurred during the first quarter of 2020. During the first quarter of 2019 , the Company completed several non-monetary acreage trades of primarily undeveloped properties located in Howard, Martin, and Midland Counties, Texas, resulting in the exchange of approximately 2,000 net acres, with $65.8 million of carrying value attributed to the properties transferred by the Company. These trades were recorded at carryover basis with no gain or loss recognized.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 4 - Income Taxes The provision for income taxes for the three months ended March 31, 2020 , and 2019 , consisted of the following: For the Three Months Ended March 31, 2020 2019 (in thousands) Current portion of income tax (expense) benefit: Federal $ — $ — State (339 ) (965 ) Deferred portion of income tax benefit 99,347 47,003 Income tax benefit $ 99,008 $ 46,038 Effective tax rate 19.4 % 20.6 % Recorded income tax expense or benefit differs from the amounts that would be provided by applying the statutory United States federal income tax rate to income or loss before income taxes. These differences primarily relate to the effect of state income taxes, excess tax benefits and deficiencies from stock-based compensation awards, tax limitations on the compensation of covered individuals, changes in valuation allowances, and the cumulative impact of other smaller permanent differences. The quarterly rate can also be affected by the proportional impacts of forecasted net income or loss for each period presented, as reflected in the table above. A change in the Company’s effective tax rate between reporting periods will generally reflect differences in estimating permanent differences compared to changes in forecasted net income or loss. Each quarter, the Company evaluates its deferred tax assets for potential realization, weighing both positive and negative evidence to determine, on a more likely than not basis, the future utilization by asset and jurisdiction. When the significance of negative evidence outweighs the Company’s positive support of realization, a valuation allowance is recorded. The Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted on March 27, 2020. The primary feature of the CARES Act that the Company will benefit from is the acceleration of its refundable Alternative Minimum Tax (“AMT”) credits. On April 1, 2020, the Company filed an election to accelerate its remaining refundable AMT credits of $7.6 million that are expected to be received during the second quarter of 2020. For all years before 2015, the Company is generally no longer subject to United States federal or state income tax examinations by tax authorities.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Long-Term Debt	Note 5 - Long-Term Debt Credit Agreement On April 29, 2020 , the Company and its lenders entered into the Third Amendment to the Credit Agreement (“Third Amendment”). The Company’s Credit Agreement provides for a senior secured revolving credit facility with a maximum loan amount of $2.5 billion . Also on April 29, 2020 , as a result of the regular semi-annual borrowing base redetermination, the borrowing base and aggregate lender commitments were both reduced to $1.1 billion due to a decrease in the value of proved reserves driven by decreased commodity pricing. The Third Amendment permits the Company to incur second lien debt of up to $900.0 million (“Permitted Lien Debt”) prior to the next scheduled redetermination date of October 1, 2020 , provided that all principal amounts of such debt are used to redeem unsecured senior debt of the Company for less than or equal to par value. Additionally, the Third Amendment reduces the limit on the amount of dividends that the Company may declare and pay on an annual basis from $50.0 million to $12.0 million . The Third Amendment also amends certain other covenants of the Company in the Credit Agreement. The Credit Agreement is scheduled to mature on September 28, 2023 , except that, pursuant to the Third Amendment, upon the Company’s incurrence of Permitted Lien Debt to redeem the 6.125% Senior Notes due 2022 (“2022 Senior Notes”), the maturity date under the Credit Agreement will be July 2, 2023. Without regard to which maturity date is in effect, the maturity date could occur earlier on August 16, 2022, if the Company has not completed certain repurchase, redemption, or refinancing activities associated with its 2022 Senior Notes, and does not have certain unused availability for borrowing under the Credit Agreement, as outlined in the Credit Agreement and the Third Amendment. The Company must comply with certain financial and non-financial covenants under the terms of the Credit Agreement and was in compliance with all such covenants as of March 31, 2020 , and through the filing of this report. Interest and commitment fees associated with the revolving credit facility are accrued based on a borrowing base utilization grid set forth in the Credit Agreement. The borrowing base utilization grid was amended by the Third Amendment as presented in the table below. Please refer to Note 5 - Long-Term Debt in the 2019 Form 10-K for the utilization grid in effect prior to the Third Amendment. At the Company’s election, borrowings under the Credit Agreement may be in the form of Eurodollar, Alternate Base Rate (“ABR”), or Swingline loans. Eurodollar loans accrue interest at LIBOR, plus the applicable margin from the utilization grid, and ABR and Swingline loans accrue interest at a market-based floating rate, plus the applicable margin from the utilization grid. Commitment fees are accrued on the unused portion of the aggregate lender commitment amount at rates from the utilization grid and are included in the interest expense line item on the accompanying statements of operations. Please refer to Note 5 - Long-Term Debt in the 2019 Form 10-K for additional detail on the terms of the Company’s Credit Agreement. Borrowing Base Utilization Percentage <25% ≥25% <50% ≥50% <75% ≥75% <90% ≥90% Eurodollar Loans (1) 1.750 % 2.000 % 2.500 % 2.750 % 3.000 % ABR Loans or Swingline Loans 0.750 % 1.000 % 1.500 % 1.750 % 2.000 % Commitment Fee Rate 0.375 % 0.375 % 0.500 % 0.500 % 0.500 % ____________________________________________ (1) The Credit Agreement specifies that in the event that LIBOR is no longer a widely used benchmark rate, or that it is no longer used for determining interest rates for loans in the United States, a replacement interest rate that fairly reflects the cost to the lenders of funding loans shall be established by the Administrative Agent, as defined in the Credit Agreement, in consultation with the Company. Please refer to Note 1 - Summary of Significant Accounting Policies for discussion of FASB ASU 2020-04, which provides guidance related to reference rate reform . The following table presents the outstanding balance, total amount of letters of credit outstanding, and available borrowing capacity under the Credit Agreement as of filing on April 29, 2020 , March 31, 2020 , and December 31, 2019 : As of filing on April 29, 2020 As of March 31, 2020 As of December 31, 2019 (in thousands) Revolving credit facility (1) $ 93,500 $ 72,000 $ 122,500 Letters of credit — — — Available borrowing capacity 1,006,500 1,128,000 1,077,500 Total aggregate lender commitment amount $ 1,100,000 $ 1,200,000 $ 1,200,000 ____________________________________________ (1) Unamortized deferred financing costs attributable to the revolving credit facility are presented as a component of the other noncurrent assets line item on the accompanying balance sheets and totaled $5.5 million and $5.9 million as of March 31, 2020 , and December 31, 2019 , respectively. These costs are being amortized over the term of the revolving credit facility on a straight-line basis. Senior Notes The Senior Notes, net of unamortized deferred financing costs line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , consisted of the following: As of March 31, 2020 As of December 31, 2019 Principal Amount Unamortized Deferred Financing Costs Principal Amount, Net of Unamortized Deferred Financing Costs Principal Amount Unamortized Deferred Financing Costs Principal Amount, Net of Unamortized Deferred Financing Costs (in thousands) 6.125% Senior Notes due 2022 $ 436,047 $ 2,442 $ 433,605 $ 476,796 $ 2,920 $ 473,876 5.0% Senior Notes due 2024 500,000 3,535 496,465 500,000 3,766 496,234 5.625% Senior Notes due 2025 500,000 4,677 495,323 500,000 4,903 495,097 6.75% Senior Notes due 2026 500,000 5,362 494,638 500,000 5,571 494,429 6.625% Senior Notes due 2027 500,000 6,368 493,632 500,000 6,601 493,399 Total $ 2,436,047 $ 22,384 $ 2,413,663 $ 2,476,796 $ 23,761 $ 2,453,035 The senior notes listed above (collectively referred to as the “Senior Notes”) are unsecured senior obligations and rank equal in right of payment with all of the Company’s existing and any future unsecured senior debt and are senior in right of payment to any future subordinated debt. There are no subsidiary guarantors of any of the Senior Notes. The Company is subject to certain covenants under the indentures governing the Senior Notes and was in compliance with all covenants as of March 31, 2020 , and through the filing of this report. The Company may redeem some or all of its Senior Notes prior to their maturity at redemption prices based on a premium, plus accrued and unpaid interest as described in the indentures governing the Senior Notes. Please refer to Note 5 - Long-Term Debt in the 2019 Form 10-K for additional detail on the Company’s Senior Notes. During the first quarter of 2020, the Company repurchased a total of $40.7 million in aggregate principal amount of its 2022 Senior Notes in open market transactions for a total settlement amount, excluding accrued interest, of $28.3 million . In connection with the repurchase, the Company recorded a gain on extinguishment of debt of $12.2 million for the three months ended March 31, 2020. This amount included discounts realized upon repurchase of $12.4 million partially offset by approximately $235,000 of accelerated unamortized deferred financing costs. The Company canceled all repurchased 2022 Senior Notes upon cash settlement. Senior Convertible Notes As of March 31, 2020 , the Company’s senior convertible notes consisted of $172.5 million in aggregate principal amount of 1.50% Senior Convertible Notes due July 1, 2021 (the “Senior Convertible Notes”). The Senior Convertible Notes are unsecured senior obligations and rank equal in right of payment with all of the Company’s existing and any future unsecured senior debt and are senior in right of payment to any future subordinated debt. Please refer to Note 5 - Long-Term Debt in the 2019 Form 10-K for additional detail on the Company’s Senior Convertible Notes and associated capped call transactions. The Senior Convertible Notes were not convertible at the option of holders as of March 31, 2020 , or through the filing of this report. Notwithstanding the inability to convert, the if-converted value of the Senior Convertible Notes as of March 31, 2020 , did not exceed the principal amount. The debt discount and debt-related issuance costs are amortized to the principal value of the Senior Convertible Notes as interest expense through the maturity date of July 1, 2021 . Interest expense recognized on the Senior Convertible Notes related to the stated interest rate and amortization of the debt discount totaled $2.9 million and $2.7 million for the three months ended March 31, 2020 , and 2019 , respectively. There have been no changes to the initial net carrying amount of the equity component of the Senior Convertible Notes recorded in additional paid-in capital on the accompanying balance sheets since issuance. The Senior Convertible Notes, net of unamortized discount and deferred financing costs line on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , consisted of the following: As of March 31, 2020 As of December 31, 2019 (in thousands) Principal amount of Senior Convertible Notes $ 172,500 $ 172,500 Unamortized debt discount (11,633 ) (13,861 ) Unamortized deferred financing costs (1,146 ) (1,376 ) Senior Convertible Notes, net of unamortized discount and deferred financing costs $ 159,721 $ 157,263 The Company is subject to certain covenants under the indenture governing the Senior Convertible Notes and was in compliance with all covenants as of March 31, 2020 , and through the filing of this report. Capitalized Interest Capitalized interest costs for the three months ended March 31, 2020 , and 2019 , totaled $2.7 million and $4.9 million , respectively. The amount of interest the Company capitalizes generally fluctuates based on the amount borrowed, the Company’s capital program, and the timing and amount of costs associated with capital projects that are considered in progress. Capitalized interest costs are included in total costs incurred.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 6 - Commitments and Contingencies Commitments Other than those items discussed below, there have been no changes in commitments through the filing of this report that differ materially from those disclosed in the 2019 Form 10-K. Please refer to Note 6 - Commitments and Contingencies in the 2019 Form 10-K for additional discussion of the Company’s commitments. Subsequent to March 31, 2020 , the Company amended certain of its drilling rig contracts resulting in the reduction of day rates and potential early termination fees and the extension of contract terms. As of the filing of this report, the Company’s drilling rig commitments totaled $22.3 million . If all of these contracts were terminated as of the filing of this report, the Company would avoid a portion of the contractual service commitments; however, the Company would be required to pay $12.9 million in early termination fees. The Company does not expect to incur material penalties with regard to its drilling rig contracts. Subsequent to March 31, 2020 , the Company entered into an agreement that included minimum drilling and completion footage requirements on certain existing leases. If these minimum requirements are not satisfied by March 31, 2021, the Company would be required to pay liquidated damages based on the difference between the actual footage drilled and completed and the minimum requirements. The liquidated damages could range from zero to a maximum of $42.0 million , with the maximum exposure assuming no development activity occurred prior to March 31, 2021 . As of the filing of this report, the Company expects to meet its obligations under this agreement. Contingencies The Company is subject to litigation and claims arising in the ordinary course of business. The Company accrues for such items when a liability is both probable and the amount can be reasonably estimated. In the opinion of management, the anticipated results of any pending litigation and claims are not expected to have a material effect on the results of operations, the financial position, or the cash flows of the Company.

Compensation Plans

Compensation Plans	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Compensation Plans	Note 7 - Compensation Plans Equity Incentive Compensation Plan As of March 31, 2020 , 4.5 million shares of common stock were available for grant under the Company’s Equity Incentive Compensation Plan (“Equity Plan”). Performance Share Units The Company grants performance share units (“PSUs”) to eligible employees as part of its Equity Plan. The number of shares of the Company’s common stock issued to settle PSUs ranges from zero to two times the number of PSUs awarded and is determined based on certain performance criteria over a three -year performance period. PSUs generally vest on the third anniversary of the date of the grant or upon other triggering events as set forth in the Equity Plan. For PSUs granted in 2017, which the Company has determined to be equity awards, the settlement criteria include a combination of the Company’s Total Shareholder Return (“TSR”) on an absolute basis, and the Company’s TSR relative to the TSR of certain peer companies over the associated three -year performance period. The fair value of the PSUs granted in 2017 was measured on the grant date using a stochastic Monte Carlo simulation using geometric Brownian motion (“GBM Model”). As these awards depend entirely on market-based settlement criteria, the associated compensation expense is recognized on a straight-line basis within general and administrative expense and exploration expense over the vesting periods of the respective awards. For PSUs granted in 2018 and 2019, the settlement criteria include a combination of the Company’s TSR relative to the TSR of certain peer companies and the Company’s cash return on total capital invested (“CRTCI”) relative to the CRTCI of certain peer companies over the associated three-year performance period. In addition to these performance measures, the award agreements for these grants also stipulate that if the Company’s absolute TSR is negative over the three-year performance period, the maximum number of shares of common stock that can be issued to settle outstanding PSUs is capped at one times the number of PSUs granted on the award date, regardless of the Company’s TSR and CRTCI performance relative to its peer group. The fair value of the PSUs granted in 2018 and 2019 was measured on the applicable grant dates using the GBM Model, with the assumption that the associated CRTCI performance condition will be met at the target amount at the end of the respective performance periods. Compensation expense for PSUs granted in 2018 and 2019 is recognized within general and administrative expense and exploration expense over the vesting periods of the respective awards. As these awards depend on a combination of performance-based settlement criteria and market-based settlement criteria, compensation expense may be adjusted in future periods as the number of units expected to vest increases or decreases based on the Company’s expected CRTCI performance relative to the applicable peer companies. The Company records compensation expense associated with the issuance of PSUs based on the fair value of the awards as of the date of grant. Total compensation expense recorded for PSUs was $2.6 million and $2.8 million for the three months ended March 31, 2020 , and 2019 , respectively. As of March 31, 2020 , there was $12.9 million of total unrecognized compensation expense related to non-vested PSU awards, which is being amortized through 2022 . There have been no material changes to the outstanding and non-vested PSUs during the three months ended March 31, 2020 . Employee Restricted Stock Units The Company grants restricted stock units (“RSUs”) to eligible persons as part of its Equity Plan. Each RSU represents a right to receive one share of the Company’s common stock upon settlement of the award at the end of the specified vesting period. RSUs generally vest one-third of the total grant on each anniversary date of the grant over a three -year vesting period or upon other triggering events as set forth in the Equity Plan. The Company records compensation expense associated with the issuance of RSUs based on the fair value of the awards as of the date of grant. The fair value of an RSU is equal to the closing price of the Company’s common stock on the day of the grant. Compensation expense for RSUs is recognized within general and administrative expense and exploration expense over the vesting periods of the respective awards. Total compensation expense recorded for employee RSUs was $2.6 million and $2.7 million for the three months ended March 31, 2020 , and 2019 , respectively. As of March 31, 2020 , there was $13.6 million of total unrecognized compensation expense related to non-vested RSU awards, which is being amortized through 2022 . There have been no material changes to the outstanding and non-vested RSUs during the three months ended March 31, 2020 . Please refer to Note 7 - Compensation Plans in the 2019 Form 10-K for additional detail on the Company’s Equity Plan.

Pension Benefits

Pension Benefits	3 Months Ended
	Mar. 31, 2020
Defined Benefit Plan [Abstract]
Pension Benefits	Note 8 - Pension Benefits Pension Plans The Company has a non-contributory defined benefit pension plan covering employees who meet age and service requirements and who began employment with the Company prior to January 1, 2016 (the “Qualified Pension Plan”). The Company also has a supplemental non-contributory pension plan covering certain management employees (the “Nonqualified Pension Plan” and together with the Qualified Pension Plan, the “Pension Plans”). The Company froze the Pension Plans to new participants, effective as of January 1, 2016. Employees participating in the Pension Plans prior to the plans being frozen will continue to earn benefits. Components of Net Periodic Benefit Cost for the Pension Plans For the Three Months Ended 2020 2019 (in thousands) Components of net periodic benefit cost: Service cost $ 1,395 $ 1,683 Interest cost 698 656 Expected return on plan assets that reduces periodic pension benefit cost (393 ) (466 ) Amortization of prior service cost 4 4 Amortization of net actuarial loss 240 332 Net periodic benefit cost $ 1,944 $ 2,209 Prior service costs are amortized on a straight-line basis over the average remaining service period of active participants. Gains and losses in excess of 10 percent of the greater of the benefit obligation or the market-related value of assets are amortized over the average remaining service period of active participants. The service cost component of net periodic benefit cost for the Pension Plans is presented as an operating expense within the general and administrative and exploration expense line items on the accompanying statements of operations while the other components of net periodic benefit cost for the Pension Plans are presented as non-operating expenses within the other non-operating expense, net line item on the accompanying statements of operations. Contributions As of the filing of this report, the Company has contributed $3.3 million to the Qualified Pension Plan in 2020.

Earnings per Share

Earnings per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Earnings per Share	Note 9 - Earnings Per Share Basic net income or loss per common share is calculated by dividing net income or loss available to common stockholders by the basic weighted-average number of common shares outstanding for the respective period. Diluted net income or loss per common share is calculated by dividing net income or loss available to common stockholders by the diluted weighted-average number of common shares outstanding, which includes the effect of potentially dilutive securities. Potentially dilutive securities for this calculation consist primarily of non-vested RSUs, contingent PSUs, and shares into which the Senior Convertible Notes are convertible, which are measured using the treasury stock method. Shares of the Company’s common stock traded at an average closing price below the $40.50 conversion price for the three months ended March 31, 2020 , and 2019 , therefore, the Senior Convertible Notes had no dilutive impact. Please refer to Note 9 - Earnings Per Share in the 2019 Form 10-K for additional detail on these potentially dilutive securities. When the Company recognizes a net loss from continuing operations, all potentially dilutive shares are anti-dilutive and are consequently excluded from the calculation of diluted net loss per common share. The following table details the weighted-average anti-dilutive securities for the periods presented: For the Three Months Ended March 31, 2020 2019 (in thousands) Anti-dilutive 1,219 781 The following table sets forth the calculations of basic and diluted net loss per common share: For the Three Months Ended March 31, 2020 2019 (in thousands, except per share data) Net loss $ (411,895 ) $ (177,568 ) Basic weighted-average common shares outstanding 113,009 112,252 Dilutive effect of non-vested RSUs and contingent PSUs — — Diluted weighted-average common shares outstanding 113,009 112,252 Basic net loss per common share $ (3.64 ) $ (1.58 ) Diluted net loss per common share $ (3.64 ) $ (1.58 )

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2020
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Derivative Financial Instruments	Note 10 - Derivative Financial Instruments Summary of Oil, Gas, and NGL Derivative Contracts in Place The Company has entered into various commodity derivative contracts to mitigate a portion of its exposure to potentially adverse market changes in commodity prices and the associated impact on cash flows. As of March 31, 2020 , all derivative counterparties were members of the Company’s Credit Agreement lender group and all contracts were entered into for other-than-trading purposes. The Company’s commodity derivative contracts consist of swap and collar arrangements for oil production, and swap arrangements for gas and NGL production. In a typical commodity swap agreement, if the agreed upon published third-party index price (“index price”) is lower than the swap fixed price, the Company receives the difference between the index price and the agreed upon swap fixed price. If the index price is higher than the swap fixed price, the Company pays the difference. For collar arrangements, the Company receives the difference between an agreed upon index price and the floor price if the index price is below the floor price. The Company pays the difference between the agreed upon ceiling price and the index price if the index price is above the ceiling price. No amounts are paid or received if the index price is between the floor and ceiling prices. The Company has also entered into fixed price oil basis swaps in order to mitigate exposure to adverse pricing differentials between certain industry benchmark prices and the actual physical pricing points where the Company’s production volumes are sold. Currently, the Company has basis swap contracts with fixed price differentials between New York Mercantile Exchange (“NYMEX”) WTI and WTI Midland for a portion of its Midland Basin production with sales contracts that settle at WTI Midland prices. The Company also has basis swaps with fixed price differentials between NYMEX WTI and Intercontinental Exchange Brent Crude (“ICE Brent”) for a portion of its Midland Basin oil production with sales contracts that settle at ICE Brent prices. As of March 31, 2020 , the Company had commodity derivative contracts outstanding through the fourth quarter of 2022 as summarized in the tables below. Oil Swaps Contract Period NYMEX WTI Volumes Weighted-Average Contract Price (MBbl) (per Bbl) Second quarter 2020 2,838 $ 58.81 Third quarter 2020 3,361 $ 56.43 Fourth quarter 2020 4,397 $ 57.03 2021 2,085 $ 45.70 Total 12,681 Oil Collars Contract Period NYMEX WTI Volumes Weighted-Average Floor Price Weighted-Average Ceiling Price (MBbl) (per Bbl) (per Bbl) Second quarter 2020 1,881 $ 55.00 $ 62.17 Third quarter 2020 1,252 $ 55.00 $ 62.90 Fourth quarter 2020 610 $ 55.00 $ 61.90 2021 329 $ 55.00 $ 56.70 Total 4,072 Oil Basis Swaps Contract Period WTI Midland-NYMEX WTI Volumes Weighted-Average Contract Price (1) NYMEX WTI-ICE Brent Volumes Weighted-Average (2) (MBbl) (per Bbl) (MBbl) (per Bbl) Second quarter 2020 3,637 $ (0.62 ) 910 $ (8.06 ) Third quarter 2020 3,607 $ (0.62 ) 920 $ (8.01 ) Fourth quarter 2020 4,087 $ (0.38 ) 920 $ (8.01 ) 2021 11,527 $ 0.87 3,650 $ (7.86 ) 2022 9,500 $ 1.15 3,650 $ (7.78 ) Total 32,358 10,050 ____________________________________________ (1) Represents the price differential between WTI Midland (Midland, Texas) and NYMEX WTI (Cushing, Oklahoma). (2) Represents the price differential between NYMEX WTI (Cushing, Oklahoma) and ICE Brent (North Sea). Gas Swaps Contract Period IF HSC Volumes Weighted-Average Contract Price WAHA Volumes Weighted-Average Contract Price (BBtu) (per MMBtu) (BBtu) (per MMBtu) Second quarter 2020 4,160 $ 2.20 3,592 $ 0.63 Third quarter 2020 4,493 $ 2.41 4,294 $ 1.07 Fourth quarter 2020 6,994 $ 2.32 4,516 $ 1.20 2021 28,621 $ 2.29 17,533 $ 1.45 2022 6,104 $ 2.23 — $ — Total (1) 50,372 29,935 ____________________________________________ (1) The Company has natural gas swaps in place that settle against Inside FERC Houston Ship Channel (“IF HSC”), Inside FERC West Texas (“IF WAHA”), and Platt’s Gas Daily West Texas (“GD WAHA”). As of March 31, 2020 , WAHA volumes were comprised of 81 percent IF WAHA and 19 percent GD WAHA . NGL Swaps OPIS Ethane Purity Mont Belvieu OPIS Propane Mont Belvieu Non-TET Contract Period Volumes Weighted-Average Contract Price Volumes Weighted-Average (MBbl) (per Bbl) (MBbl) (per Bbl) Second quarter 2020 264 $ 11.13 382 $ 22.34 Third quarter 2020 — $ — 409 $ 22.33 Fourth quarter 2020 — $ — 466 $ 22.29 Total 264 1,257 Commodity Derivative Contracts Entered Into Subsequent to March 31, 2020 Subsequent to March 31, 2020 , the Company entered into the following commodity derivative contracts: • fixed price NYMEX WTI oil swap contracts for 2021 for a total of 5.5 MMBbl of oil production at a weighted-average contract price of $37.57 per Bbl; • fixed price IF HSC gas swap contracts for 2021 for a total of 6,197 BBtu of gas production at a weighted-average contract price of $2.42 per MMBtu; • fixed price IF WAHA gas swap contracts through the fourth quarter of 2021 for a total of 2,437 BBtu of gas production at a weighted-average contract price of $1.57 per MMBtu; and • crude oil swap contracts to fix the differential in pricing between the NYMEX calendar month average and the physical crude oil delivery month (“Roll Differential”) for the second quarter of 2020 through the fourth quarter of 2021 for a total of 6.8 MMBbl of oil production, in which the Company pays the periodic variable Roll Differential and receives a weighted-average fixed price of $(1.24) per Bbl; the weighted average price differential represents the amount of net addition (reduction) to delivery month prices for the notional volumes covered by the swap contracts. Derivative Assets and Liabilities Fair Value The Company’s commodity derivatives are measured at fair value and are included in the accompanying balance sheets as derivative assets and liabilities, with the exception of derivative instruments that meet the “normal purchase normal sale” exclusion. The Company does not designate its derivative commodity contracts as hedging instruments. The fair value of the commodity derivative contracts was a net asset of $493.4 million and $21.5 million as of March 31, 2020 , and December 31, 2019 , respectively. The following table details the fair value of commodity derivative contracts recorded in the accompanying balance sheets, by category: As of March 31, 2020 As of December 31, 2019 (in thousands) Derivative assets: Current assets $ 463,992 $ 55,184 Noncurrent assets 44,909 20,624 Total derivative assets $ 508,901 $ 75,808 Derivative liabilities: Current liabilities $ 8,277 $ 50,846 Noncurrent liabilities 7,202 3,444 Total derivative liabilities $ 15,479 $ 54,290 Offsetting of Derivative Assets and Liabilities As of March 31, 2020 , and December 31, 2019 , all derivative instruments held by the Company were subject to master netting arrangements with various financial institutions. In general, the terms of the Company’s agreements provide for offsetting of amounts payable or receivable between it and the counterparty, at the election of both parties, for transactions that settle on the same date and in the same currency. The Company’s agreements also provide that in the event of an early termination, the counterparties have the right to offset amounts owed or owing under that and any other agreement with the same counterparty. The Company’s accounting policy is to not offset these positions in its accompanying balance sheets. The following table provides a reconciliation between the gross assets and liabilities reflected on the accompanying balance sheets and the potential effects of master netting arrangements on the fair value of the Company’s commodity derivative contracts: Derivative Assets as of Derivative Liabilities as of March 31, 2020 December 31, 2019 March 31, 2020 December 31, 2019 (in thousands) Gross amounts presented in the accompanying balance sheets $ 508,901 $ 75,808 $ (15,479 ) $ (54,290 ) Amounts not offset in the accompanying balance sheets (15,479 ) (35,075 ) 15,479 35,075 Net amounts $ 493,422 $ 40,733 $ — $ (19,215 ) The following table summarizes the commodity components of the derivative settlement (gain) loss, as well as the components of the net derivative (gain) loss line item presented in the accompanying statements of operations: For the Three Months Ended March 31, 2020 2019 (in thousands) Derivative settlement (gain) loss: Oil contracts $ (53,582 ) $ 1,369 Gas contracts (14,625 ) 4,134 NGL contracts (5,230 ) (534 ) Total derivative settlement (gain) loss $ (73,437 ) $ 4,969 Net derivative (gain) loss: Oil contracts $ (542,540 ) $ 185,797 Gas contracts 6,728 (6,113 ) NGL contracts (9,528 ) (2,603 ) Total net derivative (gain) loss $ (545,340 ) $ 177,081 Credit Related Contingent Features As of March 31, 2020 , and through the filing of this report, all of the Company’s derivative counterparties were members of the Company’s Credit Agreement lender group. Under the Credit Agreement, the Company is required to provide mortgage liens on assets having a value equal to at least 85 percent of the total PV-9, as defined in the Credit Agreement, of the Company’s proved oil and gas properties evaluated in the most recent reserve report. Collateral securing indebtedness under the Credit Agreement also secures the Company’s derivative agreement obligations.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Note 11 - Fair Value Measurements The Company follows fair value measurement accounting guidance for all assets and liabilities measured at fair value. This guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Market or observable inputs are the preferred sources of values, followed by assumptions based on hypothetical transactions in the absence of market inputs. The fair value hierarchy for grouping these assets and liabilities is based on the significance level of the following inputs: • Level 1 – quoted prices in active markets for identical assets or liabilities • Level 2 – quoted prices in active markets for similar assets or 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 The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of March 31, 2020 : Level 1 Level 2 Level 3 (in thousands) Assets: Derivatives (1) $ — $ 508,901 $ — Total property and equipment, net (2) $ — $ — $ 380,734 Liabilities: Derivatives (1) $ — $ 15,479 $ — __________________________________________ (1) This represents a financial asset or liability that is measured at fair value on a recurring basis. (2) This represents a non-financial asset that is measured at fair value on a nonrecurring basis. The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of December 31, 2019 : Level 1 Level 2 Level 3 (in thousands) Assets: Derivatives (1) $ — $ 75,808 $ — Liabilities: Derivatives (1) $ — $ 54,290 $ — ____________________________________________ (1) This represents a financial asset or liability that is measured at fair value on a recurring basis. Both financial and non-financial assets and liabilities are categorized within the above fair value hierarchy based on the lowest level of input that is significant to the fair value measurement. The following is a description of the valuation methodologies used by the Company as well as the general classification of such instruments pursuant to the above fair value hierarchy. Derivatives The Company uses Level 2 inputs to measure the fair value of oil, gas, and NGL commodity derivatives. Fair values are based upon interpolated data. The Company derives internal valuation estimates taking into consideration forward commodity price curves, counterparties’ credit ratings, the Company’s credit rating, and the time value of money. These valuations are then compared to the respective counterparties’ mark-to-market statements. The considered factors result in an estimated exit price that management believes provides a reasonable and consistent methodology for valuing derivative instruments. The commodity derivative instruments utilized by the Company are not considered by management to be complex, structured, or illiquid. The oil, gas, and NGL commodity derivative markets are highly active. Please refer to Note 10 - Derivative Financial Instruments , and to Note 11 - Fair Value Measurements in the 2019 Form 10-K for more information regarding the Company’s derivative instruments. Oil and Gas Properties and Other Property and Equipment Amounts reflected in the total property and equipment, net line item, measured at fair value within the accompanying balance sheets totaled $380.7 million as of March 31, 2020 . The Company had no assets included in total property and equipment, net, measured at fair value as of December 31, 2019 . Proved oil and gas properties . Proved oil and gas property costs are evaluated for impairment and reduced to fair value when there is an indication that associated carrying costs may not be recoverable. The Company uses an income valuation technique, which converts future cash flows to a single present value amount, to measure the fair value of proved properties using a discount rate, price and cost forecasts, and certain reserve risk-adjustment factors, as selected by the Company’s management. The Company uses a discount rate that represents a current market-based weighted average cost of capital. The prices for oil and gas are forecast based on NYMEX strip pricing, adjusted for basis differentials, for the first five years, after which a flat terminal price is used for each commodity stream. The prices for NGLs are forecasted using Oil Price Information Service (“OPIS”) Mont Belvieu pricing, for as long as the market is actively trading, after which a flat terminal price is used. Future operating costs are also adjusted as deemed appropriate for these estimates. Certain undeveloped reserve estimates are also risk-adjusted given the risk to related projected cash flows due to performance and exploitation uncertainties. Other Property and Equipment. Other property and equipment costs are evaluated for impairment and reduced to fair value when there is an indication the carrying costs may not be recoverable. To measure the fair value of other property and equipment, the Company uses an income valuation technique or market approach depending on the quality of information available to support management’s assumptions and the circumstances. The valuation includes consideration of the proved and unproved assets supported by the property and equipment, future cash flows associated with the assets, and fixed costs necessary to operate and maintain the assets. As a result of the decrease in commodity price forecasts at the end of the first quarter of 2020, specifically decreases in oil and NGL prices, the Company recorded impairment expense of $956.7 million related to its South Texas proved oil and gas properties and related support facilities during the three months ended March 31, 2020 . The Company used a discount rate of 11 percent in its calculation of the present value of expected future cash flows based on the prevailing market-based weighted average cost of capital as of March 31, 2020 . No proved property impairment expense was recorded during the three months ended March 31, 2019 . The following table presents impairment of oil and gas properties expense and abandonment and impairment of unproved properties expense recorded for the periods presented: For the Three Months Ended 2020 2019 (in millions) Impairment of proved oil and gas properties and related support equipment $ 956.7 $ — Abandonment and impairment of unproved properties (1) 33.1 6.3 Impairment $ 989.8 $ 6.3 ____________________________________________ (1) These impairments related to actual and anticipated lease expirations, as well as actual and anticipated losses on acreage due to title defects, changes in development plans, and other inherent acreage risks. The balances in the unproved oil and gas properties line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , are recorded at carrying value. Please refer to Note 1 - Summary of Significant Accounting Policies and Note 11 - Fair Value Measurements in the 2019 Form 10-K for more information regarding the Company’s approach in determining the fair value of its properties. Long-Term Debt The following table reflects the fair value of the Company’s unsecured senior note obligations measured using Level 1 inputs based on quoted secondary market trading prices. These notes were not presented at fair value on the accompanying balance sheets as of March 31, 2020 , or December 31, 2019 , as they were recorded at carrying value, net of any unamortized discounts and deferred financing costs. Please refer to Note 5 - Long-Term Debt for additional discussion. As of March 31, 2020 As of December 31, 2019 Principal Amount Fair Value Principal Amount Fair Value (in thousands) 6.125% Senior Notes due 2022 $ 436,047 $ 190,771 $ 476,796 $ 481,564 5.0% Senior Notes due 2024 $ 500,000 $ 148,750 $ 500,000 $ 479,815 5.625% Senior Notes due 2025 $ 500,000 $ 145,000 $ 500,000 $ 475,835 6.75% Senior Notes due 2026 $ 500,000 $ 150,000 $ 500,000 $ 494,860 6.625% Senior Notes due 2027 $ 500,000 $ 149,215 $ 500,000 $ 493,750 1.50% Senior Convertible Notes due 2021 $ 172,500 $ 69,576 $ 172,500 $ 164,430 The carrying value of the Company’s revolving credit facility approximates its fair value, as the applicable interest rates are floating, based on prevailing market rates.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
Lessee Disclosure [Abstract]
Leases	Note 12 - Leases ASC Topic 842 - Leases (“Topic 842”), requires lessees to recognize operating and finance leases with terms greater than 12 months on the balance sheet. As of March 31, 2020 , the Company did not have any agreements in place that were classified as finance leases under Topic 842. Arrangements classified as operating leases are included on the accompanying balance sheets within the other noncurrent assets, other current liabilities, and other noncurrent liabilities line items. As outlined in Topic 842, an ROU asset represents a lessee’s right to use an underlying asset for the lease term, while the associated lease liability represents the lessee’s obligations to make lease payments. At the commencement date, which is the date on which a lessor makes an underlying asset available for use by a lessee, a lease ROU asset and corresponding lease liability is recognized based on the present value of the future lease payments. Excluded from the initial measurement are certain variable lease payments, which for the Company’s drilling rigs, completion crews, and midstream agreements, may be a significant component of the total lease costs. Subsequent to initial measurement, costs associated with the Company’s operating leases are either expensed on the accompanying statements of operations or capitalized on the accompanying balance sheets depending on the nature and use of the underlying ROU asset and in accordance with GAAP requirements. Please refer to Note 12 - Leases in the 2019 Form 10-K for more information regarding the Company's policy on leases, and assumptions and judgments made in the initial and subsequent measurement of lease ROU assets and corresponding liabilities. Currently, the Company has operating leases for asset classes that include office space, office equipment, drilling rigs, midstream agreements, vehicles, and equipment rentals used in field operations. For those operating leases included on the accompanying balance sheets, which only includes leases with terms greater than 12 months at commencement, remaining lease terms range from less than one year to approximately six years . The weighted-average lease term remaining for these leases is approximately three years . Certain leases also contain optional extension periods that allow for terms to be extended for up to an additional ten years . An early termination option also exists for certain leases, some of which allow for the Company to terminate a lease within one year. Exercising an early termination option may also result in an early termination penalty depending on the terms of the underlying agreement. Based on expectations for those agreements with early termination options, there are no leases in which material early termination options are reasonably certain to be exercised by the Company. For the three months ended March 31, 2020 , and 2019 , total costs related to operating leases, including short-term leases, and variable lease payments made for leases with initial lease terms greater than 12 months, were $72.7 million and $175.3 million , respectively. These totals do not reflect amounts that may be reimbursed by other third parties in the normal course of business, such as non-operating working interest owners. Components of the Company’s total lease cost, whether capitalized or expensed, for the three months ended March 31, 2020 , and 2019 , consisted of the following: For the Three Months Ended March 31, 2020 2019 (in thousands) Operating lease cost $ 6,834 $ 8,979 Short-term lease cost (1) 43,572 134,917 Variable lease cost (2) 22,334 31,408 Total lease cost $ 72,740 $ 175,304 ____________________________________________ (1) Costs associated with short-term lease agreements relate primarily to operational activities where underlying lease terms are less than one year. This amount is significant as it includes drilling and completion activities and field equipment rentals, most of which are contracted for 12 months or less. It is expected that this amount will fluctuate primarily with the number of drilling rigs and completion crews the Company is operating under short-term agreements. (2) Variable lease payments include additional payments made that were not included in the initial measurement of the ROU asset and corresponding liability for lease agreements with terms longer than 12 months. Variable lease payments relate to the actual volumes transported under certain midstream agreements, actual usage associated with drilling rigs, completion crews, and vehicles, and variable utility costs associated with the Company’s leased office space. Fluctuations in variable lease payments are driven by actual volumes delivered and the number of drilling rigs and completion crews operating under long-term agreements. Other information related to the Company’s leases for the three months ended March 31, 2020 , and 2019 , was as follows: For the Three Months Ended March 31, 2020 2019 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,046 $ 2,952 Investing cash flows from operating leases $ 3,980 $ 6,182 Right-of-use assets obtained in exchange for new operating lease liabilities $ — $ 12,191 Maturities for the Company’s operating lease liabilities included on the accompanying balance sheets as of March 31, 2020 , were as follows: As of March 31, 2020 (in thousands) 2020 (remaining after March 31, 2020) $ 13,997 2021 12,541 2022 5,745 2023 3,602 2024 2,081 Thereafter 1,640 Total Lease payments $ 39,606 Less: Imputed interest (1) (3,816 ) Total $ 35,790 ____________________________________________ (1) The weighted-average discount rate used to determine the operating lease liability as of March 31, 2020 , was 6.7 percent . Amounts recorded on the accompanying balance sheets for operating leases as of March 31, 2020 , and December 31, 2019 , were as follows: As of March 31, 2020 As of December 31, 2019 (in thousands) Other noncurrent assets $ 33,365 $ 39,717 Other current liabilities $ 15,780 $ 19,189 Other noncurrent liabilities $ 20,010 $ 23,137 As of March 31, 2020 , and through the filing of this report, the Company has no material lease arrangements which are scheduled to commence in the future.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation, Policy [Policy Text Block]	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information, the instructions to Quarterly Report on Form 10-Q, and Regulation S-X. These financial statements do not include all information and notes required by GAAP for annual financial statements. However, except as disclosed herein, there has been no material change in the information disclosed in the notes to the consolidated financial statements included in the 2019 Form 10-K. In the opinion of management, all adjustments, consisting of normal recurring adjustments considered necessary for a fair presentation of interim financial information, have been included. Operating results for the periods presented are not necessarily indicative of expected results for the full year. In connection with the preparation of the Company’s unaudited condensed consolidated financial statements, the Company evaluated events subsequent to the balance sheet date of March 31, 2020 , and through the filing of this report. Additionally, certain prior period amounts have been reclassified to conform to current period presentation in the accompanying unaudited condensed consolidated financial statements.
Recently Issued Accounting Standards, Policy [Policy Text Block]	Recently Issued Accounting Standards In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 was issued to reduce the complexity of accounting for income taxes for those entities that fall within the scope of the accounting standard. The guidance is to be applied using a prospective method, excluding amendments related to franchise taxes, which should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company early adopted ASU 2019-12 on January 1, 2020, and there was no material impact on the Company’s unaudited condensed consolidated financial statements or disclosures upon adoption. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”). ASU 2020-04 was issued to provide optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. Generally, the guidance is to be applied as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. ASU 2020-04 is effective for all entities as of March 12, 2020 through December 31, 2022. The Company is evaluating the options provided by ASU 2020-04. Please refer to Note 5 - Long-Term Debt for discussion of the use of the London Interbank Offered Rate (“LIBOR”) in connection with borrowings under the Credit Agreement. As disclosed in the 2019 Form 10-K, the Company adopted ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract on January 1, 2020. As expected, there was no material impact on the Company’s unaudited condensed consolidated financial statements or disclosures upon adoption of these ASUs. There are no ASUs that would have a material effect on the Company’s unaudited condensed consolidated financial statements and related disclosures that have been issued but not yet adopted by the Company as of March 31, 2020 , and through the filing of this report.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Derivatives The Company uses Level 2 inputs to measure the fair value of oil, gas, and NGL commodity derivatives. Fair values are based upon interpolated data. The Company derives internal valuation estimates taking into consideration forward commodity price curves, counterparties’ credit ratings, the Company’s credit rating, and the time value of money. These valuations are then compared to the respective counterparties’ mark-to-market statements. The considered factors result in an estimated exit price that management believes provides a reasonable and consistent methodology for valuing derivative instruments. The commodity derivative instruments utilized by the Company are not considered by management to be complex, structured, or illiquid. The oil, gas, and NGL commodity derivative markets are highly active. Please refer to Note 10 - Derivative Financial Instruments , and to Note 11 - Fair Value Measurements in the 2019 Form 10-K for more information regarding the Company’s derivative instruments.
Property, Plant and Equipment, Impairment, Policy [Policy Text Block]	Oil and Gas Properties and Other Property and Equipment Amounts reflected in the total property and equipment, net line item, measured at fair value within the accompanying balance sheets totaled $380.7 million as of March 31, 2020 . The Company had no assets included in total property and equipment, net, measured at fair value as of December 31, 2019 . Proved oil and gas properties . Proved oil and gas property costs are evaluated for impairment and reduced to fair value when there is an indication that associated carrying costs may not be recoverable. The Company uses an income valuation technique, which converts future cash flows to a single present value amount, to measure the fair value of proved properties using a discount rate, price and cost forecasts, and certain reserve risk-adjustment factors, as selected by the Company’s management. The Company uses a discount rate that represents a current market-based weighted average cost of capital. The prices for oil and gas are forecast based on NYMEX strip pricing, adjusted for basis differentials, for the first five years, after which a flat terminal price is used for each commodity stream. The prices for NGLs are forecasted using Oil Price Information Service (“OPIS”) Mont Belvieu pricing, for as long as the market is actively trading, after which a flat terminal price is used. Future operating costs are also adjusted as deemed appropriate for these estimates. Certain undeveloped reserve estimates are also risk-adjusted given the risk to related projected cash flows due to performance and exploitation uncertainties. Other Property and Equipment. Other property and equipment costs are evaluated for impairment and reduced to fair value when there is an indication the carrying costs may not be recoverable. To measure the fair value of other property and equipment, the Company uses an income valuation technique or market approach depending on the quality of information available to support management’s assumptions and the circumstances. The valuation includes consideration of the proved and unproved assets supported by the property and equipment, future cash flows associated with the assets, and fixed costs necessary to operate and maintain the assets. As a result of the decrease in commodity price forecasts at the end of the first quarter of 2020, specifically decreases in oil and NGL prices, the Company recorded impairment expense of $956.7 million related to its South Texas proved oil and gas properties and related support facilities during the three months ended March 31, 2020 . The Company used a discount rate of 11 percent in its calculation of the present value of expected future cash flows based on the prevailing market-based weighted average cost of capital as of March 31, 2020 . No proved property impairment expense was recorded during the three months ended March 31, 2019 . The following table presents impairment of oil and gas properties expense and abandonment and impairment of unproved properties expense recorded for the periods presented: For the Three Months Ended 2020 2019 (in millions) Impairment of proved oil and gas properties and related support equipment $ 956.7 $ — Abandonment and impairment of unproved properties (1) 33.1 6.3 Impairment $ 989.8 $ 6.3 ____________________________________________ (1) These impairments related to actual and anticipated lease expirations, as well as actual and anticipated losses on acreage due to title defects, changes in development plans, and other inherent acreage risks. The balances in the unproved oil and gas properties line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , are recorded at carrying value.
Leases, Policy [Policy Text Block]	Arrangements classified as operating leases are included on the accompanying balance sheets within the other noncurrent assets, other current liabilities, and other noncurrent liabilities line items. As outlined in Topic 842, an ROU asset represents a lessee’s right to use an underlying asset for the lease term, while the associated lease liability represents the lessee’s obligations to make lease payments. At the commencement date, which is the date on which a lessor makes an underlying asset available for use by a lessee, a lease ROU asset and corresponding lease liability is recognized based on the present value of the future lease payments. Excluded from the initial measurement are certain variable lease payments, which for the Company’s drilling rigs, completion crews, and midstream agreements, may be a significant component of the total lease costs. Subsequent to initial measurement, costs associated with the Company’s operating leases are either expensed on the accompanying statements of operations or capitalized on the accompanying balance sheets depending on the nature and use of the underlying ROU asset and in accordance with GAAP requirements. Please refer to Note 12 - Leases in the 2019 Form 10-K for more information regarding the Company's policy on leases, and assumptions and judgments made in the initial and subsequent measurement of lease ROU assets and corresponding liabilities.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of oil, gas, and NGL production revenue [Table Text Block]	The table below presents oil, gas, and NGL production revenue by product type for each of the Company’s operating regions for the three months ended March 31, 2020 , and 2019 : Midland Basin South Texas Total Three Months Ended March 31, Three Months Ended March 31, Three Months Ended March 31, 2020 2019 2020 2019 2020 2019 (in thousands) Oil production revenue $ 276,136 $ 225,247 $ 15,557 $ 13,814 $ 291,693 $ 239,061 Gas production revenue 11,334 15,592 29,376 49,521 40,710 65,113 NGL production revenue 58 21 21,772 36,281 21,830 36,302 Total $ 287,528 $ 240,860 $ 66,705 $ 99,616 $ 354,233 $ 340,476 Relative percentage 81 % 71 % 19 % 29 % 100 % 100 % ____________________________________________ Note: Amounts may not calculate due to rounding.

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of provision for income taxes [Table Text Block]	The provision for income taxes for the three months ended March 31, 2020 , and 2019 , consisted of the following: For the Three Months Ended March 31, 2020 2019 (in thousands) Current portion of income tax (expense) benefit: Federal $ — $ — State (339 ) (965 ) Deferred portion of income tax benefit 99,347 47,003 Income tax benefit $ 99,008 $ 46,038 Effective tax rate 19.4 % 20.6 %

Long-Term Debt (Tables)

Long-Term Debt (Tables)	Apr. 29, 2020	Mar. 31, 2020
Line of Credit Facility [Table Text Blocks]
Schedule of Credit Agreement Facilities [Table Text Block]		The following table presents the outstanding balance, total amount of letters of credit outstanding, and available borrowing capacity under the Credit Agreement as of filing on April 29, 2020 , March 31, 2020 , and December 31, 2019 : As of filing on April 29, 2020 As of March 31, 2020 As of December 31, 2019 (in thousands) Revolving credit facility (1) $ 93,500 $ 72,000 $ 122,500 Letters of credit — — — Available borrowing capacity 1,006,500 1,128,000 1,077,500 Total aggregate lender commitment amount $ 1,100,000 $ 1,200,000 $ 1,200,000 ____________________________________________ (1) Unamortized deferred financing costs attributable to the revolving credit facility are presented as a component of the other noncurrent assets line item on the accompanying balance sheets and totaled $5.5 million and $5.9 million as of March 31, 2020 , and December 31, 2019 , respectively. These costs are being amortized over the term of the revolving credit facility on a straight-line basis.
Schedule of Senior Notes [Table Text Block]		The Senior Notes, net of unamortized deferred financing costs line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , consisted of the following: As of March 31, 2020 As of December 31, 2019 Principal Amount Unamortized Deferred Financing Costs Principal Amount, Net of Unamortized Deferred Financing Costs Principal Amount Unamortized Deferred Financing Costs Principal Amount, Net of Unamortized Deferred Financing Costs (in thousands) 6.125% Senior Notes due 2022 $ 436,047 $ 2,442 $ 433,605 $ 476,796 $ 2,920 $ 473,876 5.0% Senior Notes due 2024 500,000 3,535 496,465 500,000 3,766 496,234 5.625% Senior Notes due 2025 500,000 4,677 495,323 500,000 4,903 495,097 6.75% Senior Notes due 2026 500,000 5,362 494,638 500,000 5,571 494,429 6.625% Senior Notes due 2027 500,000 6,368 493,632 500,000 6,601 493,399 Total $ 2,436,047 $ 22,384 $ 2,413,663 $ 2,476,796 $ 23,761 $ 2,453,035
Schedule of Senior Convertible Notes [Table Text Block]		The Senior Convertible Notes, net of unamortized discount and deferred financing costs line on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , consisted of the following: As of March 31, 2020 As of December 31, 2019 (in thousands) Principal amount of Senior Convertible Notes $ 172,500 $ 172,500 Unamortized debt discount (11,633 ) (13,861 ) Unamortized deferred financing costs (1,146 ) (1,376 ) Senior Convertible Notes, net of unamortized discount and deferred financing costs $ 159,721 $ 157,263
Subsequent Event [Member]
Line of Credit Facility [Table Text Blocks]
Schedule of Borrowing Base Utilization [Table Text Block]	Borrowing Base Utilization Percentage <25% ≥25% <50% ≥50% <75% ≥75% <90% ≥90% Eurodollar Loans (1) 1.750 % 2.000 % 2.500 % 2.750 % 3.000 % ABR Loans or Swingline Loans 0.750 % 1.000 % 1.500 % 1.750 % 2.000 % Commitment Fee Rate 0.375 % 0.375 % 0.500 % 0.500 % 0.500 % ____________________________________________ (1) The Credit Agreement specifies that in the event that LIBOR is no longer a widely used benchmark rate, or that it is no longer used for determining interest rates for loans in the United States, a replacement interest rate that fairly reflects the cost to the lenders of funding loans shall be established by the Administrative Agent, as defined in the Credit Agreement, in consultation with the Company. Please refer to Note 1 - Summary of Significant Accounting Policies for discussion of FASB ASU 2020-04, which provides guidance related to reference rate reform .

Pension Benefits (Tables)

Pension Benefits (Tables)	3 Months Ended
	Mar. 31, 2020
Defined Benefit Plan [Abstract]
Components of the net periodic benefit cost for the pension plans [Table Text Block]	Components of Net Periodic Benefit Cost for the Pension Plans For the Three Months Ended 2020 2019 (in thousands) Components of net periodic benefit cost: Service cost $ 1,395 $ 1,683 Interest cost 698 656 Expected return on plan assets that reduces periodic pension benefit cost (393 ) (466 ) Amortization of prior service cost 4 4 Amortization of net actuarial loss 240 332 Net periodic benefit cost $ 1,944 $ 2,209

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of anti-dilutive securities excluded from computation of earnings per share [Table Text Block]	The following table details the weighted-average anti-dilutive securities for the periods presented: For the Three Months Ended March 31, 2020 2019 (in thousands) Anti-dilutive 1,219 781
Schedule of calculations of basic and diluted net loss per common share [Table Text Block]	The following table sets forth the calculations of basic and diluted net loss per common share: For the Three Months Ended March 31, 2020 2019 (in thousands, except per share data) Net loss $ (411,895 ) $ (177,568 ) Basic weighted-average common shares outstanding 113,009 112,252 Dilutive effect of non-vested RSUs and contingent PSUs — — Diluted weighted-average common shares outstanding 113,009 112,252 Basic net loss per common share $ (3.64 ) $ (1.58 ) Diluted net loss per common share $ (3.64 ) $ (1.58 )

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Schedule of notional amounts of outstanding derivative positions [Table Text Block]	As of March 31, 2020 , the Company had commodity derivative contracts outstanding through the fourth quarter of 2022 as summarized in the tables below. Oil Swaps Contract Period NYMEX WTI Volumes Weighted-Average Contract Price (MBbl) (per Bbl) Second quarter 2020 2,838 $ 58.81 Third quarter 2020 3,361 $ 56.43 Fourth quarter 2020 4,397 $ 57.03 2021 2,085 $ 45.70 Total 12,681 Oil Collars Contract Period NYMEX WTI Volumes Weighted-Average Floor Price Weighted-Average Ceiling Price (MBbl) (per Bbl) (per Bbl) Second quarter 2020 1,881 $ 55.00 $ 62.17 Third quarter 2020 1,252 $ 55.00 $ 62.90 Fourth quarter 2020 610 $ 55.00 $ 61.90 2021 329 $ 55.00 $ 56.70 Total 4,072 Oil Basis Swaps Contract Period WTI Midland-NYMEX WTI Volumes Weighted-Average Contract Price (1) NYMEX WTI-ICE Brent Volumes Weighted-Average (2) (MBbl) (per Bbl) (MBbl) (per Bbl) Second quarter 2020 3,637 $ (0.62 ) 910 $ (8.06 ) Third quarter 2020 3,607 $ (0.62 ) 920 $ (8.01 ) Fourth quarter 2020 4,087 $ (0.38 ) 920 $ (8.01 ) 2021 11,527 $ 0.87 3,650 $ (7.86 ) 2022 9,500 $ 1.15 3,650 $ (7.78 ) Total 32,358 10,050 ____________________________________________ (1) Represents the price differential between WTI Midland (Midland, Texas) and NYMEX WTI (Cushing, Oklahoma). (2) Represents the price differential between NYMEX WTI (Cushing, Oklahoma) and ICE Brent (North Sea). Gas Swaps Contract Period IF HSC Volumes Weighted-Average Contract Price WAHA Volumes Weighted-Average Contract Price (BBtu) (per MMBtu) (BBtu) (per MMBtu) Second quarter 2020 4,160 $ 2.20 3,592 $ 0.63 Third quarter 2020 4,493 $ 2.41 4,294 $ 1.07 Fourth quarter 2020 6,994 $ 2.32 4,516 $ 1.20 2021 28,621 $ 2.29 17,533 $ 1.45 2022 6,104 $ 2.23 — $ — Total (1) 50,372 29,935 ____________________________________________ (1) The Company has natural gas swaps in place that settle against Inside FERC Houston Ship Channel (“IF HSC”), Inside FERC West Texas (“IF WAHA”), and Platt’s Gas Daily West Texas (“GD WAHA”). As of March 31, 2020 , WAHA volumes were comprised of 81 percent IF WAHA and 19 percent GD WAHA . NGL Swaps OPIS Ethane Purity Mont Belvieu OPIS Propane Mont Belvieu Non-TET Contract Period Volumes Weighted-Average Contract Price Volumes Weighted-Average (MBbl) (per Bbl) (MBbl) (per Bbl) Second quarter 2020 264 $ 11.13 382 $ 22.34 Third quarter 2020 — $ — 409 $ 22.33 Fourth quarter 2020 — $ — 466 $ 22.29 Total 264 1,257
Schedule of fair value of derivatives in accompanying balance sheets [Table Text Block]	The following table details the fair value of commodity derivative contracts recorded in the accompanying balance sheets, by category: As of March 31, 2020 As of December 31, 2019 (in thousands) Derivative assets: Current assets $ 463,992 $ 55,184 Noncurrent assets 44,909 20,624 Total derivative assets $ 508,901 $ 75,808 Derivative liabilities: Current liabilities $ 8,277 $ 50,846 Noncurrent liabilities 7,202 3,444 Total derivative liabilities $ 15,479 $ 54,290
Schedule of the potential effects of master netting arrangements [Table Text Block]	The following table provides a reconciliation between the gross assets and liabilities reflected on the accompanying balance sheets and the potential effects of master netting arrangements on the fair value of the Company’s commodity derivative contracts: Derivative Assets as of Derivative Liabilities as of March 31, 2020 December 31, 2019 March 31, 2020 December 31, 2019 (in thousands) Gross amounts presented in the accompanying balance sheets $ 508,901 $ 75,808 $ (15,479 ) $ (54,290 ) Amounts not offset in the accompanying balance sheets (15,479 ) (35,075 ) 15,479 35,075 Net amounts $ 493,422 $ 40,733 $ — $ (19,215 )
Schedule of the components of the derivative settlement (gain) loss and of the net derivative (gain) loss [Table Text Block]	The following table summarizes the commodity components of the derivative settlement (gain) loss, as well as the components of the net derivative (gain) loss line item presented in the accompanying statements of operations: For the Three Months Ended March 31, 2020 2019 (in thousands) Derivative settlement (gain) loss: Oil contracts $ (53,582 ) $ 1,369 Gas contracts (14,625 ) 4,134 NGL contracts (5,230 ) (534 ) Total derivative settlement (gain) loss $ (73,437 ) $ 4,969 Net derivative (gain) loss: Oil contracts $ (542,540 ) $ 185,797 Gas contracts 6,728 (6,113 ) NGL contracts (9,528 ) (2,603 ) Total net derivative (gain) loss $ (545,340 ) $ 177,081

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table Text Block]	The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of March 31, 2020 : Level 1 Level 2 Level 3 (in thousands) Assets: Derivatives (1) $ — $ 508,901 $ — Total property and equipment, net (2) $ — $ — $ 380,734 Liabilities: Derivatives (1) $ — $ 15,479 $ — __________________________________________ (1) This represents a financial asset or liability that is measured at fair value on a recurring basis. (2) This represents a non-financial asset that is measured at fair value on a nonrecurring basis. The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of December 31, 2019 : Level 1 Level 2 Level 3 (in thousands) Assets: Derivatives (1) $ — $ 75,808 $ — Liabilities: Derivatives (1) $ — $ 54,290 $ — ____________________________________________ (1) This represents a financial asset or liability that is measured at fair value on a recurring basis.
Impairment of oil and gas properties [Table Text Block]	The following table presents impairment of oil and gas properties expense and abandonment and impairment of unproved properties expense recorded for the periods presented: For the Three Months Ended 2020 2019 (in millions) Impairment of proved oil and gas properties and related support equipment $ 956.7 $ — Abandonment and impairment of unproved properties (1) 33.1 6.3 Impairment $ 989.8 $ 6.3 ____________________________________________ (1) These impairments related to actual and anticipated lease expirations, as well as actual and anticipated losses on acreage due to title defects, changes in development plans, and other inherent acreage risks. The balances in the unproved oil and gas properties line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , are recorded at carrying value.
Long Term Debt Fair Value [Table Text Block]	The following table reflects the fair value of the Company’s unsecured senior note obligations measured using Level 1 inputs based on quoted secondary market trading prices. These notes were not presented at fair value on the accompanying balance sheets as of March 31, 2020 , or December 31, 2019 , as they were recorded at carrying value, net of any unamortized discounts and deferred financing costs. Please refer to Note 5 - Long-Term Debt for additional discussion. As of March 31, 2020 As of December 31, 2019 Principal Amount Fair Value Principal Amount Fair Value (in thousands) 6.125% Senior Notes due 2022 $ 436,047 $ 190,771 $ 476,796 $ 481,564 5.0% Senior Notes due 2024 $ 500,000 $ 148,750 $ 500,000 $ 479,815 5.625% Senior Notes due 2025 $ 500,000 $ 145,000 $ 500,000 $ 475,835 6.75% Senior Notes due 2026 $ 500,000 $ 150,000 $ 500,000 $ 494,860 6.625% Senior Notes due 2027 $ 500,000 $ 149,215 $ 500,000 $ 493,750 1.50% Senior Convertible Notes due 2021 $ 172,500 $ 69,576 $ 172,500 $ 164,430

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Lessee Disclosure [Abstract]
Components of total lease cost [Table Text Block]	Components of the Company’s total lease cost, whether capitalized or expensed, for the three months ended March 31, 2020 , and 2019 , consisted of the following: For the Three Months Ended March 31, 2020 2019 (in thousands) Operating lease cost $ 6,834 $ 8,979 Short-term lease cost (1) 43,572 134,917 Variable lease cost (2) 22,334 31,408 Total lease cost $ 72,740 $ 175,304 ____________________________________________ (1) Costs associated with short-term lease agreements relate primarily to operational activities where underlying lease terms are less than one year. This amount is significant as it includes drilling and completion activities and field equipment rentals, most of which are contracted for 12 months or less. It is expected that this amount will fluctuate primarily with the number of drilling rigs and completion crews the Company is operating under short-term agreements. (2) Variable lease payments include additional payments made that were not included in the initial measurement of the ROU asset and corresponding liability for lease agreements with terms longer than 12 months. Variable lease payments relate to the actual volumes transported under certain midstream agreements, actual usage associated with drilling rigs, completion crews, and vehicles, and variable utility costs associated with the Company’s leased office space. Fluctuations in variable lease payments are driven by actual volumes delivered and the number of drilling rigs and completion crews operating under long-term agreements. Other information related to the Company’s leases for the three months ended March 31, 2020 , and 2019 , was as follows: For the Three Months Ended March 31, 2020 2019 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,046 $ 2,952 Investing cash flows from operating leases $ 3,980 $ 6,182 Right-of-use assets obtained in exchange for new operating lease liabilities $ — $ 12,191
Operating lease liability maturities [Table Text Block]	Maturities for the Company’s operating lease liabilities included on the accompanying balance sheets as of March 31, 2020 , were as follows: As of March 31, 2020 (in thousands) 2020 (remaining after March 31, 2020) $ 13,997 2021 12,541 2022 5,745 2023 3,602 2024 2,081 Thereafter 1,640 Total Lease payments $ 39,606 Less: Imputed interest (1) (3,816 ) Total $ 35,790 ____________________________________________ (1) The weighted-average discount rate used to determine the operating lease liability as of March 31, 2020 , was 6.7 percent .
Balance Sheet information related to operating leases [Table Text Block]	Amounts recorded on the accompanying balance sheets for operating leases as of March 31, 2020 , and December 31, 2019 , were as follows: As of March 31, 2020 As of December 31, 2019 (in thousands) Other noncurrent assets $ 33,365 $ 39,717 Other current liabilities $ 15,780 $ 19,189 Other noncurrent liabilities $ 20,010 $ 23,137

Disaggregation of oil, gas, and

Disaggregation of oil, gas, and NGL production revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 354,233	$ 340,476
Revenue, Remaining Performance Obligation, Amount	0
Oil production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	291,693	239,061
Gas production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	40,710	65,113
NGL production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	21,830	36,302
Midland Basin [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	287,528	240,860
Midland Basin [Member] | Oil production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	276,136	225,247
Midland Basin [Member] | Gas production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	11,334	15,592
Midland Basin [Member] | NGL production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	58	21
South Texas [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	66,705	99,616
South Texas [Member] | Oil production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15,557	13,814
South Texas [Member] | Gas production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	29,376	49,521
South Texas [Member] | NGL production revenue [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 21,772	$ 36,281
Revenue Benchmark [Member] | Geographic Concentration Risk [Member]
Segment Reporting Information [Line Items]
Relative percentage	100.00%	100.00%
Revenue Benchmark [Member] | Geographic Concentration Risk [Member] | Midland Basin [Member]
Segment Reporting Information [Line Items]
Relative percentage	81.00%	71.00%
Revenue Benchmark [Member] | Geographic Concentration Risk [Member] | South Texas [Member]
Segment Reporting Information [Line Items]
Relative percentage	19.00%	29.00%

Accounts Receivable from Custom

Accounts Receivable from Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable [Line Items]
Accounts receivable from contracts with customers	$ 143,311	$ 184,732
Oil, gas, and NGL production revenue [Member]
Accounts Receivable [Line Items]
Accounts receivable from contracts with customers	$ 62,000	$ 146,300
Minimum [Member]
Accounts Receivable [Line Items]
Revenue Receipt, Days After Sale	30
Maximum [Member]
Accounts Receivable [Line Items]
Revenue Receipt, Days After Sale	90

Divestitures and Assets Held fo

Divestitures and Assets Held for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Divestitures, Assets Held for Sale, and Acquisitions [Abstract]
Properties held for sale, net	$ 0	$ 0

Nonmonetary Transactions (Detai

Nonmonetary Transactions (Details)	3 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)a
Nonmonetary Transactions [Abstract]
Net acres exchanged | a		2,000
Carrying value of properties exchanged	$ 0	$ 65,788,000
Basis of accounting for assets exchanged		carryover
Gain (loss) recognized on trade		$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Components of the provision for income taxes
Federal	$ 0	$ 0
State	(339)	(965)
Deferred portion of income tax benefit	99,347	47,003
Income tax benefit	$ 99,008	$ 46,038
Effective tax rate	19.40%	20.60%
Proceeds expected from income tax refunds	$ 7,600

Revolving Credit Facility (Deta

Revolving Credit Facility (Details) - USD ($) $ in Thousands		Apr. 29, 2020	Mar. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Revolving credit facility			$ 72,000	$ 122,500
Revolving Credit Facility [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, dividend restrictions, amount			50,000
Revolving credit facility, aggregate lender commitments			1,200,000	1,200,000
Revolving credit facility	[1]		72,000	122,500
Letters of credit			0	0
Available borrowing capacity			1,128,000	1,077,500
Revolving credit facility, unamortized deferred financing costs			$ 5,500	$ 5,900
Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, maximum loan amount		$ 2,500,000
Revolving credit facility, current borrowing base		1,100,000
Revolving credit facility, dividend restrictions, amount		12,000
Revolving credit facility, aggregate lender commitments		1,100,000
Revolving credit facility		93,500
Letters of credit		0
Available borrowing capacity		1,006,500
Revolving Credit Facility [Member] | Second Lien Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, current borrowing base		$ 900,000
Borrowing Base Utilization Of Less Than 25 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, unused capacity, commitment fee rate		0.375%
Borrowing Base Utilization Of 25 Percent Or More But Less Than 50 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, unused capacity, commitment fee rate		0.375%
Borrowing Base Utilization Of 50 Percent Or More But Less Than 75 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, unused capacity, commitment fee rate		0.50%
Borrowing Base Utilization Of 75 Percent Or More But Less Than 90 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, unused capacity, commitment fee rate		0.50%
Borrowing Base Utilization Of 90 Percent Or More [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, unused capacity, commitment fee rate		0.50%
Eurodollar [Member] | Borrowing Base Utilization Of Less Than 25 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate	[2]	1.75%
Eurodollar [Member] | Borrowing Base Utilization Of 25 Percent Or More But Less Than 50 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate	[2]	2.00%
Eurodollar [Member] | Borrowing Base Utilization Of 50 Percent Or More But Less Than 75 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate	[2]	2.50%
Eurodollar [Member] | Borrowing Base Utilization Of 75 Percent Or More But Less Than 90 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate	[2]	2.75%
Eurodollar [Member] | Borrowing Base Utilization Of 90 Percent Or More [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate	[2]	3.00%
Prime Rate [Member] | Borrowing Base Utilization Of Less Than 25 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate		0.75%
Prime Rate [Member] | Borrowing Base Utilization Of 25 Percent Or More But Less Than 50 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate		1.00%
Prime Rate [Member] | Borrowing Base Utilization Of 50 Percent Or More But Less Than 75 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate		1.50%
Prime Rate [Member] | Borrowing Base Utilization Of 75 Percent Or More But Less Than 90 Percent [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate		1.75%
Prime Rate [Member] | Borrowing Base Utilization Of 90 Percent Or More [Member] | Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate		2.00%
[1]	(1) Unamortized deferred financing costs attributable to the revolving credit facility are presented as a component of the other noncurrent assets line item on the accompanying balance sheets and totaled $5.5 million and $5.9 million as of March 31, 2020 , and December 31, 2019 , respectively. These costs are being amortized over the term of the revolving credit facility on a straight-line basis.
[2]	(1) The Credit Agreement specifies that in the event that LIBOR is no longer a widely used benchmark rate, or that it is no longer used for determining interest rates for loans in the United States, a replacement interest rate that fairly reflects the cost to the lenders of funding loans shall be established by the Administrative Agent, as defined in the Credit Agreement, in consultation with the Company. Please refer to Note 1 - Summary of Significant Accounting Policies for discussion of FASB ASU 2020-04, which provides guidance related to reference rate reform .

Senior Notes (Details)

Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Senior Notes [Line Items]
Principal Amount, Net of Unamortized Deferred Financing Costs	$ 2,413,663		$ 2,453,035
Gain on extinguishment of debt	12,195	$ 0
Capitalized interest costs	$ 2,700	$ 4,900
6.125% Senior Notes due 2022 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.125%
Principal amount	$ 436,047		476,796
Unamortized deferred financing costs	(2,442)		(2,920)
Principal Amount, Net of Unamortized Deferred Financing Costs	433,605		473,876
Senior Notes, repurchased face amount	40,700
Senior Notes, repurchased settlement amount	28,300
Gain on extinguishment of debt	12,200
Discount realized on extinguishment of debt	12,400
Accelerated unamortized deferred financing costs on extinguishment of debt	$ 235
5.0% Senior Notes due 2024 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	5.00%
Principal amount	$ 500,000		500,000
Unamortized deferred financing costs	(3,535)		(3,766)
Principal Amount, Net of Unamortized Deferred Financing Costs	$ 496,465		496,234
5.625% Senior Notes due 2025 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	5.625%
Principal amount	$ 500,000		500,000
Unamortized deferred financing costs	(4,677)		(4,903)
Principal Amount, Net of Unamortized Deferred Financing Costs	$ 495,323		495,097
6.75% Senior Notes due 2026 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.75%
Principal amount	$ 500,000		500,000
Unamortized deferred financing costs	(5,362)		(5,571)
Principal Amount, Net of Unamortized Deferred Financing Costs	$ 494,638		494,429
6.625% Senior Notes due 2027 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.625%
Principal amount	$ 500,000		500,000
Unamortized deferred financing costs	(6,368)		(6,601)
Principal Amount, Net of Unamortized Deferred Financing Costs	493,632		493,399
Senior Notes
Senior Notes [Line Items]
Principal amount	2,436,047		2,476,796
Unamortized deferred financing costs	(22,384)		(23,761)
Principal Amount, Net of Unamortized Deferred Financing Costs	$ 2,413,663		$ 2,453,035

Senior Convertible Notes (Detai

Senior Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Senior Convertibles Notes [Line Items]
Senior Convertible Notes, net of unamortized discount and deferred financing costs	$ 159,721		$ 157,263
1.50% Senior Convertible Notes Due 2021 [Member]
Senior Convertibles Notes [Line Items]
Senior Convertible Notes, principal amount	$ 172,500		172,500
Senior Convertible Notes, interest rate, stated percentage	1.50%
Senior Convertible Notes, interest expense	$ 2,900	$ 2,700
Senior Convertible Notes, unamortized debt discount	(11,633)		(13,861)
Senior Convertible Notes, unamortized deferred financing costs	(1,146)		(1,376)
Senior Convertible Notes, net of unamortized discount and deferred financing costs	$ 159,721		$ 157,263

Commitments (Details)

Commitments (Details) - Subsequent Event [Member] $ in Millions	Apr. 28, 2020USD ($)
Minimum [Member]
Commitments and Contingencies [Line Items]
Potential penalty for not meeting minimum drilling and completion requirements	$ 0
Maximum [Member]
Commitments and Contingencies [Line Items]
Potential penalty for not meeting minimum drilling and completion requirements	42
Drilling Rig Leasing Contracts [Member]
Commitments and Contingencies [Line Items]
Contractual Obligation	22.3
Early Termination Penalty for Rig Contract Cancellation	$ 12.9

Compensation Plans_ Stock Based

Compensation Plans: Stock Based (Details) $ in Millions	Mar. 31, 2020USD ($)shares	Mar. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share available for grant | shares	4,500,000	4,500,000
Performance Shares (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Stock-based compensation expense		$ 2.6	$ 2.8
Unrecognized stock based compensation expense	$ 12.9	$ 12.9
Performance Shares (PSUs) | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier applied to PSU awards at settlement	0	0
Performance Shares (PSUs) | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier applied to PSU awards at settlement	2	2
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Stock-based compensation expense		$ 2.6	$ 2.7
Unrecognized stock based compensation expense	$ 13.6	$ 13.6
Number of shares represented by each RSU | shares	1	1

Pension Benefits (Details)

Pension Benefits (Details) - USD ($) $ in Thousands	Apr. 28, 2020	Mar. 31, 2020	Mar. 31, 2019
Components of Net Periodic Benefit Costs for the Pension Plans
Service cost		$ 1,395	$ 1,683
Interest cost		698	656
Expected return on plan assets that reduces periodic pension benefit cost		(393)	(466)
Amortization of prior service cost		4	4
Amortization of net actuarial loss		240	332
Net periodic benefit cost		$ 1,944	$ 2,209
Pension plans, net gain (loss) amortization threshold		10.00%
Subsequent Event [Member]
Components of Net Periodic Benefit Costs for the Pension Plans
Employer contributions	$ 3,300

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from earnings per share	1,219	781
Calculation of basic and diluted earnings per share
Net loss	$ (411,895)	$ (177,568)
Basic weighted-average common shares outstanding	113,009	112,252
Dilutive effect of non-vested RSUs and contingent PSUs	0	0
Diluted weighted-average common shares outstanding	113,009	112,252
Basic net loss per common share	$ (3.64)	$ (1.58)
Diluted net loss per common share	(3.64)	(1.58)
1.50% Senior Convertible Notes Due 2021 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Senior Convertible Notes, conversion price	$ 40.50	$ 40.50

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) bbl in Thousands, BTU in Billions		Apr. 28, 2020BTU$ / EnergyContent$ / Barrelsbbl	Mar. 31, 2020BTU$ / EnergyContent$ / Barrelsbbl
NYMEX Oil Swap Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			2,838
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			58.81
NYMEX Oil Swap Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			3,361
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			56.43
NYMEX Oil Swap Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			4,397
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			57.03
NYMEX Oil Swap Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			2,085
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			45.70
NYMEX Oil Swap Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			12,681
NYMEX Oil Collar Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			1,881
Derivative, Weighted-Average Floor Price | $ / Barrels			55
Derivative, Weighted-Average Ceiling Price | $ / Barrels			62.17
NYMEX Oil Collar Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			1,252
Derivative, Weighted-Average Floor Price | $ / Barrels			55
Derivative, Weighted-Average Ceiling Price | $ / Barrels			62.90
NYMEX Oil Collar Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			610
Derivative, Weighted-Average Floor Price | $ / Barrels			55
Derivative, Weighted-Average Ceiling Price | $ / Barrels			61.90
NYMEX Oil Collar Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			329
Derivative, Weighted-Average Floor Price | $ / Barrels			55
Derivative, Weighted-Average Ceiling Price | $ / Barrels			56.70
NYMEX Oil Collar Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			4,072
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			3,637
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[1]		(0.62)
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			3,607
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[1]		(0.62)
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			4,087
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[1]		(0.38)
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			11,527
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[1]		0.87
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract, 2022 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			9,500
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[1]		1.15
WTI Midland NYMEX WTI [Member] | Oil Basis Swap [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			32,358
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			910
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[2]		(8.06)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			920
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[2]		(8.01)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			920
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[2]		(8.01)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			3,650
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[2]		(7.86)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract, 2022 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			3,650
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels	[2]		(7.78)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			10,050
IF HSC [Member] | Gas Swaps Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			2.20
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			4,160
IF HSC [Member] | Gas Swaps Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			2.41
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			4,493
IF HSC [Member] | Gas Swaps Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			2.32
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			6,994
IF HSC [Member] | Gas Swaps Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			2.29
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			28,621
IF HSC [Member] | Gas Swaps Contract, 2022 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			2.23
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			6,104
IF HSC [Member] | Gas Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU	[3]		50,372
WAHA [Member] | Gas Swaps Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			0.63
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			3,592
WAHA [Member] | Gas Swaps Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			1.07
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			4,294
WAHA [Member] | Gas Swaps Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			1.20
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			4,516
WAHA [Member] | Gas Swaps Contract, 2021 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			1.45
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			17,533
WAHA [Member] | Gas Swaps Contract, 2022 [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent			0
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			0
WAHA [Member] | Gas Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU	[3]		29,935
IF WAHA [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps			81.00%
GD WAHA [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps			19.00%
OPIS Ethane Purity Mont Belvieu [Member] | NGL Swaps Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			264
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			11.13
OPIS Ethane Purity Mont Belvieu [Member] | NGL Swaps Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			0
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			0
OPIS Ethane Purity Mont Belvieu [Member] | NGL Swaps Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			0
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			0
OPIS Ethane Purity Mont Belvieu [Member] | NGL Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			264
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contract Second Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			382
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			22.34
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contract Third Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			409
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			22.33
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contract Fourth Quarter, 2020 [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			466
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels			22.29
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume			1,257
Subsequent Event [Member] | NYMEX Oil Swap Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume		5,500
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels		37.57
Subsequent Event [Member] | NYMEX Oil Calendar Month Average Roll Differential Contracts [Member]
Derivative Financial Instruments
Derivative, Nonmonetary Notional Amount, Volume		6,800
Derivative, Roll Differential Swap Type, Weighted-Average Contract Price | $ / Barrels		(1.24)
Subsequent Event [Member] | IF HSC [Member] | Gas Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent		2.42
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU		6,197
Subsequent Event [Member] | IF WAHA [Member] | Gas Swaps Contracts [Member]
Derivative Financial Instruments
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent		1.57
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU		2,437
[1]	(1) Represents the price differential between WTI Midland (Midland, Texas) and NYMEX WTI (Cushing, Oklahoma).
[2]	(2) Represents the price differential between NYMEX WTI (Cushing, Oklahoma) and ICE Brent (North Sea).
[3]	(1) The Company has natural gas swaps in place that settle against Inside FERC Houston Ship Channel (“IF HSC”), Inside FERC West Texas (“IF WAHA”), and Platt’s Gas Daily West Texas (“GD WAHA”). As of March 31, 2020 , WAHA volumes were comprised of 81 percent IF WAHA and 19 percent GD WAHA .

Derivative Financial Instrume_4

Derivative Financial Instruments Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020		Dec. 31, 2019
Fair value of derivative assets and liabilities
Derivative, fair value, net	$ 493,400		$ 21,500
Derivative assets, current	463,992		55,184
Derivative assets, noncurrent	44,909		20,624
Total derivative assets	508,901		75,808
Derivative liabilities, current	8,277		50,846
Derivatives liabilities, noncurrent	7,202		3,444
Total derivative liabilities	(15,479)		(54,290)
Derivative asset, amounts not offset in the accompanying balance sheets	(15,479)		(35,075)
Derivative liabilities, amounts not offset in the accompanying balance sheets	15,479		35,075
Derivative asset, fair value, net amounts	493,422		40,733
Derivative liabilities, fair value, net amounts	0		(19,215)
Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Derivative assets, current	463,992		55,184
Derivative assets, noncurrent	44,909		20,624
Derivative liabilities, current	8,277		50,846
Derivatives liabilities, noncurrent	7,202		3,444
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Total derivative assets	508,901	[1]	75,808	[2]
Total derivative liabilities	$ 15,479	[1]	$ 54,290	[2]
[1]	(1) This represents a financial asset or liability that is measured at fair value on a recurring basis.
[2]	(1) This represents a financial asset or liability that is measured at fair value on a recurring basis.

Derivative Financial Instrume_5

Derivative Financial Instruments Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	$ (73,437)	$ 4,969
Net derivative (gain) loss	(545,340)	177,081
Oil Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	(53,582)	1,369
Net derivative (gain) loss	(542,540)	185,797
Gas Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	(14,625)	4,134
Net derivative (gain) loss	6,728	(6,113)
NGL Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	(5,230)	(534)
Net derivative (gain) loss	$ (9,528)	$ (2,603)

Credit Facility and Derivative

Credit Facility and Derivative Counterparties (Details)	Mar. 31, 2020
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Percentage of proved property secured for credit facility borrowing	85.00%

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019	Dec. 31, 2019
Assets
Derivative Assets, Fair Value, Gross Asset		$ 508,901			$ 75,808
Liabilities
Derivative Liability, Fair Value, Gross Liability		15,479			54,290
Oil and Gas Property [Abstract]
Impairment of proved oil and gas properties and related support equipment		956,700		$ 0
Abandonment and impairment of unproved properties	[1]	33,100		6,300
Impairment		$ 989,763		$ 6,338
6.125% Senior Notes due 2022 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		6.125%
Principal amount		$ 436,047			476,796
Long-term Debt, Fair Value		$ 190,771			481,564
5.0% Senior Notes due 2024 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		5.00%
Principal amount		$ 500,000			500,000
Long-term Debt, Fair Value		$ 148,750			479,815
5.625% Senior Notes due 2025 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		5.625%
Principal amount		$ 500,000			500,000
Long-term Debt, Fair Value		$ 145,000			475,835
6.75% Senior Notes due 2026 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		6.75%
Principal amount		$ 500,000			500,000
Long-term Debt, Fair Value		$ 150,000			494,860
6.625% Senior Notes due 2027 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		6.625%
Principal amount		$ 500,000			500,000
Long-term Debt, Fair Value		$ 149,215			493,750
1.50% Senior Convertible Notes Due 2021 [Member]
Debt Instrument, Fair Value Disclosure [Abstract]
Senior Notes, interest rate, stated percentage		1.50%
Principal amount		$ 172,500			172,500
Long-term Debt, Fair Value		69,576			164,430
Fair Value, Nonrecurring [Member]
Assets
Total property and equipment, net, recorded at fair value	[2]				0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total property and equipment, net, recorded at fair value	[2]	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total property and equipment, net, recorded at fair value	[2]	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total property and equipment, net, recorded at fair value	[2]	380,734
Not Designated as Hedging Instrument [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Derivative Assets, Fair Value, Gross Asset		0	[3]		0	[4]
Liabilities
Derivative Liability, Fair Value, Gross Liability		0	[3]		0	[4]
Not Designated as Hedging Instrument [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Derivative Assets, Fair Value, Gross Asset		508,901	[3]		75,808	[4]
Liabilities
Derivative Liability, Fair Value, Gross Liability		(15,479)	[3]		(54,290)	[4]
Not Designated as Hedging Instrument [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Derivative Assets, Fair Value, Gross Asset		0	[3]		0	[4]
Liabilities
Derivative Liability, Fair Value, Gross Liability		$ 0	[3]		$ 0	[4]
Measurement Input, Discount Rate [Member] | Fair Value, Nonrecurring [Member]
Oil and Gas Property [Abstract]
Present value calculation discount rate		11.00%
[1]	(1) These impairments related to actual and anticipated lease expirations, as well as actual and anticipated losses on acreage due to title defects, changes in development plans, and other inherent acreage risks. The balances in the unproved oil and gas properties line item on the accompanying balance sheets as of March 31, 2020 , and December 31, 2019 , are recorded at carrying value.
[2]	(2) This represents a non-financial asset that is measured at fair value on a nonrecurring basis.
[3]	(1) This represents a financial asset or liability that is measured at fair value on a recurring basis.
[4]	(1) This represents a financial asset or liability that is measured at fair value on a recurring basis.

Lease Parameter (Details)

Lease Parameter (Details)	Mar. 31, 2020
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term	3 years
Optional extension period	10 years
Minimum [Member]
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Remaining lease term	6 years

Components of total lease cost

Components of total lease cost (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Lessee Disclosure [Abstract]
Total lease cost		$ 72,740	$ 175,304
Operating lease cost		6,834	8,979
Short-term lease cost	[1]	43,572	134,917
Variable lease cost	[2]	22,334	31,408
Operating cash flows from operating leases		3,046	2,952
Investing cash flows from operating leases		3,980	6,182
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 0	$ 12,191
[1]	(1) Costs associated with short-term lease agreements relate primarily to operational activities where underlying lease terms are less than one year. This amount is significant as it includes drilling and completion activities and field equipment rentals, most of which are contracted for 12 months or less. It is expected that this amount will fluctuate primarily with the number of drilling rigs and completion crews the Company is operating under short-term agreements.
[2]	(2) Variable lease payments include additional payments made that were not included in the initial measurement of the ROU asset and corresponding liability for lease agreements with terms longer than 12 months. Variable lease payments relate to the actual volumes transported under certain midstream agreements, actual usage associated with drilling rigs, completion crews, and vehicles, and variable utility costs associated with the Company’s leased office space. Fluctuations in variable lease payments are driven by actual volumes delivered and the number of drilling rigs and completion crews operating under long-term agreements.

Operating lease liability matur

Operating lease liability maturities (Details) $ in Thousands	Mar. 31, 2020USD ($)
Lessee Disclosure [Abstract]
Operating lease liability payments, due 2020 (remaining after March 31, 2020)	$ 13,997
Operating lease liability payments, due 2021	12,541
Operating lease liability payments, due 2022	5,745
Operating lease liability payments, due 2023	3,602
Operating lease liability payments, due 2024	2,081
Operating lease liability payments, due thereafter	1,640
Total lease payments	39,606
Imputed interest	(3,816)	[1]
Total operating lease liability	$ 35,790
Weighted-average discount rate	6.70%
[1]	(1) The weighted-average discount rate used to determine the operating lease liability as of March 31, 2020 , was 6.7 percent .

Balance Sheet information relat

Balance Sheet information related to operating leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Lessee Disclosure [Abstract]
Other noncurrent assets	$ 33,365	$ 39,717
Other current liabilities	15,780	19,189
Other noncurrent liabilities	$ 20,010	$ 23,137