Summary of Property and Equipment (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) $ / bbl	Jun. 30, 2019 USD ($) $ / bbl	Jun. 30, 2020 USD ($) $ / bbl	Jun. 30, 2019 USD ($) $ / bbl	Dec. 31, 2019 USD ($)
Property, Plant and Equipment [Abstract]
Proved Oil and Gas Property, Full Cost Method	$ 1,501,291		$ 1,501,291		$ 1,409,219
Unproved Oil and Gas Property, Full Cost Method	52,142		52,142		53,200
Oil and Gas Property, Full Cost Method, Gross	1,553,433		1,553,433		1,462,419
Total properties and equipment	1,580,903		1,580,903		1,488,334
Other property and equipment	27,470		27,470		25,915
Accumulated depreciation, depletion and amortization	(481,065)		(481,065)		(367,909)
Property and equipment, net (successful efforts method)	1,099,838		1,099,838		1,120,425
Interest Costs Capitalized		$ 1,400		$ 2,200
Unproved Oil and Gas Property excluded	52,100		52,100		$ 53,200
Undeveloped Leasehold Costs Transferred			4,400	100
Asset Impairment Charges	35,509	0	35,509	0
Capitalized Costs, Proved Properties	$ 1,200	$ 2,200	$ 1,200	$ 2,200
Amortization Expense Per Physical Unit of Production | $ / bbl	16.66	17.49	16.66	17.49