Risk Management and Derivative Instruments - Unrealized and Realized Gains and Losses Related to Derivative Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	$ (60,671)	$ 6,700
Interest expense, net	(20,522)	(16,855)
Commodity derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	(60,671)	6,700
Interest Rate Swaps [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	$ 4,044	$ (224)