Derivative Activities - Effects of Derivatives on Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Derivative Fair Value Income (Loss)	$ 64,556	$ 202,004	$ (11,334)	$ 290,052
Re-purchased Swaps
Derivative [Line Items]
Derivative Fair Value Income (Loss)	0	1,683	0	1,683
Collars
Derivative [Line Items]
Derivative Fair Value Income (Loss)	1,320	5,626	1,320	12,391
Basis Swaps
Derivative [Line Items]
Derivative Fair Value Income (Loss)	21,853	(3,550)	24,929	(5,943)
Puts
Derivative [Line Items]
Derivative Fair Value Income (Loss)	2,842	0	2,842	0
Commodity | Swaps
Derivative [Line Items]
Derivative Fair Value Income (Loss)	38,662	198,245	(40,270)	281,921
Freight | Swaps
Derivative [Line Items]
Derivative Fair Value Income (Loss)	$ (121)	$ 0	$ (155)	$ 0