SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Derivative Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Asset Derivative Financial Instruments:
Derivative Financial Instruments – current	$ 10,765	$ 8,913
Derivative Financial Instruments – long-term	830	661
Liability Derivative Financial Instruments:
Derivative Financial Instruments – current	255,127	47,005
Derivative Financial Instruments – long-term	14,157	2,364
Derivative Financial Instruments – current
Asset Derivative Financial Instruments:
Derivative Financial Instruments – current	10,765	8,913
Liability Derivative Financial Instruments:
Derivative Financial Instruments – current	255,127	47,005
Derivative Financial Instruments – long-term
Asset Derivative Financial Instruments:
Derivative Financial Instruments – long-term	830	661
Liability Derivative Financial Instruments:
Derivative Financial Instruments – long-term	14,157	2,364
Natural gas price derivatives \| Derivative Financial Instruments – current
Asset Derivative Financial Instruments:
Derivative Financial Instruments – current	6,419	8,913
Liability Derivative Financial Instruments:
Derivative Financial Instruments – current	244,304	45,158
Natural gas price derivatives \| Derivative Financial Instruments – long-term
Asset Derivative Financial Instruments:
Derivative Financial Instruments – long-term	798	661
Liability Derivative Financial Instruments:
Derivative Financial Instruments – long-term	14,157	1,308
Oil price derivatives \| Derivative Financial Instruments – current
Asset Derivative Financial Instruments:
Derivative Financial Instruments – current	4,346	0
Liability Derivative Financial Instruments:
Derivative Financial Instruments – current	9,828	831
Interest rate derivatives \| Derivative Financial Instruments – current
Liability Derivative Financial Instruments:
Derivative Financial Instruments – current	995	1,016
Interest rate derivatives \| Derivative Financial Instruments – long-term
Asset Derivative Financial Instruments:
Derivative Financial Instruments – long-term	32	0
Liability Derivative Financial Instruments:
Derivative Financial Instruments – long-term	$ 0	$ 1,056

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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