Derivative Activities - Effects of Derivatives on Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Fair Value Income (Loss)	$ 187,711	$ 226,681	$ (51,192)
Contingent Consideration
Derivative [Line Items]
Derivative Fair Value Income (Loss)	970	0	0
Swaption
Derivative [Line Items]
Derivative Fair Value Income (Loss)	(4,955)	333	(6,556)
Collars
Derivative [Line Items]
Derivative Fair Value Income (Loss)	3,304	(3,903)	17,583
Three Way Collars
Derivative [Line Items]
Derivative Fair Value Income (Loss)	(16,346)	0	0
Basis Swaps
Derivative [Line Items]
Derivative Fair Value Income (Loss)	48,278	6,661	(1,104)
Calls
Derivative [Line Items]
Derivative Fair Value Income (Loss)	(558)	(349)	(2,653)
Commodity | Swap
Derivative [Line Items]
Derivative Fair Value Income (Loss)	158,248	219,968	(57,950)
Freight | Swap
Derivative [Line Items]
Derivative Fair Value Income (Loss)	$ (1,230)	$ 3,971	$ (512)