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Derivative Financial Instruments Gains and Losses (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018
Derivative Instruments, (Gain) Loss [Line Items] |  |  |  |
Derivative settlement (gain) loss | $ (24,722) | $ 40,718 | $ (23,843) | $ 101,911
Net derivative (gain) loss | (100,889) | 178,026 | (3,463) | 249,304
Oil Contracts [Member] |  |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |  |
Derivative settlement (gain) loss | 2,246 | 16,798 | 14,304 | 61,976
Net derivative (gain) loss | (83,984) | 110,413 | 67,261 | 146,781
Gas Contracts [Member] |  |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |  |
Derivative settlement (gain) loss | (12,210) | 802 | (13,744) | (4,851)
Net derivative (gain) loss | (4,228) | 4,309 | (36,337) | 21,299
NGL Contracts [Member] |  |  |  |
Derivative Instruments, (Gain) Loss [Line Items] |  |  |  |
Derivative settlement (gain) loss | (14,758) | 23,118 | (24,403) | 44,786
Net derivative (gain) loss | $ (12,677) | $ 63,304 | $ (34,387) | $ 81,224

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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=109980867&loc=SL5618551-113959 + Details
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