Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Commodity derivative assets – current	$ 34,932	$ 0
Derivative assets	10,100	0
Liabilities:
Derivative liabilities, current	991	27,777
Derivative liabilities, noncurrent	0	(13,900)
Fair Value, Measurements, Recurring \| Commodity contracts
Assets:
Commodity derivative assets – current	34,932
Derivative assets	10,100
Liabilities:
Derivative liabilities, current	(991)	(27,777)
Derivative liabilities, noncurrent	0	(13,900)
Fair Value, Measurements, Recurring \| Commodity contracts \| Level 1
Assets:
Commodity derivative assets – current	0
Derivative assets	0
Liabilities:
Derivative liabilities, current	0	0
Derivative liabilities, noncurrent	0	0
Fair Value, Measurements, Recurring \| Commodity contracts \| Level 2
Assets:
Commodity derivative assets – current	34,932
Derivative assets	10,100
Liabilities:
Derivative liabilities, current	(991)	(27,777)
Derivative liabilities, noncurrent	0	(13,900)
Fair Value, Measurements, Recurring \| Commodity contracts \| Level 3
Assets:
Commodity derivative assets – current	0
Derivative assets	0
Liabilities:
Derivative liabilities, current	0	0
Derivative liabilities, noncurrent	$ 0	$ 0

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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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