Risk Management and Derivative Instruments - Unrealized and Realized Gains and Losses Related to Derivative Instruments (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	$ 117,105,000	$ (462,890,000)	$ (492,254,000)
Interest expense, net	146,031,000	115,154,000	83,550,000
Commodity derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
(Gain) loss on commodity derivative instruments	117,105	(462,890)	(492,254)
Interest rate derivatives [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	$ 1,290	$ 4,674	$ (151)