Risk Management and Derivative Instruments - Unrealized and Realized Gains and Losses Related to Derivative Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	$ 34,588	$ (107,713)
Interest expense, net	(3,112)	(7,647)
Commodity derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	34,588	(107,713)
Interest Rate Swaps [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	$ (62)	$ 3,616