Commodity Derivative Financial Instruments - Changes in Fair Value of Company's Commodity Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivatives not designated as hedging instruments
Gain (loss) on derivative instruments	$ (4,955)	$ 14,831	$ 26,902
Net cash (received) paid on settlements of derivative instruments	(27,862)	38,235	(15,211)
Not Designated as Hedging Instrument
Derivatives not designated as hedging instruments
Beginning fair value of commodity derivative instruments	48,038	(5,028)	(16,719)
Net change in fair value of commodity derivative instruments	(32,817)	53,066	11,691
Ending fair value of commodity derivative instruments	15,221	48,038	(5,028)
Oil \| Not Designated as Hedging Instrument
Derivatives not designated as hedging instruments
Gain (loss) on derivative instruments	(34,728)	24,300	(5,091)
Net cash (received) paid on settlements of derivative instruments	(8,536)	34,905	(10,901)
Natural Gas \| Not Designated as Hedging Instrument
Derivatives not designated as hedging instruments
Gain (loss) on derivative instruments	29,773	(9,469)	31,993
Net cash (received) paid on settlements of derivative instruments	$ (19,326)	$ 3,330	$ (4,310)

The net cash outflow or inflow from derivative instruments during the period

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- Definition

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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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

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open agreements to purchase or sell mineral resources, energy, and agricultural products at some future point held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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