Risk Management and Derivative Instruments - Unrealized and Realized Gains and Losses Related to Derivative Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivatives	$ (19,165)	$ 22,993	$ 88,548	$ (9,494)
Interest expense, net	(6,209)	(4,422)	(13,856)	(8,511)
Commodity derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivatives	19,165	(22,993)	(88,548)	9,494
Interest rate derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	$ 438	$ 627	$ 4,054	$ 534