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Derivative Financial Instruments Gains and Losses (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Derivative Instruments, (Gain) Loss [Line Items] |  |  |
Derivative settlement (gain) loss | $ (351,261) | $ (39,222) | $ 135,803
Net derivative (gain) loss | (161,576) | 97,539 | (161,832)
Oil Contracts [Member] |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |
Derivative settlement (gain) loss | (331,559) | 19,685 | 68,860
Net derivative (gain) loss | (205,180) | 172,055 | (192,002)
Gas Contracts [Member] |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |
Derivative settlement (gain) loss | (11,898) | (23,008) | 13,029
Net derivative (gain) loss | 30,038 | (41,205) | 35,411
NGL Contracts [Member] |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |
Derivative settlement (gain) loss | (7,804) | (35,899) | 53,914
Net derivative (gain) loss | $ 13,566 | $ (33,311) | $ (5,241)

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- Definition Realized gain or loss recognized in earnings from the settlement of derivative instruments not designated as hedges. + References No definition available. + Details
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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