Risk Management and Hedging Activities - Schedule of Net Long or Short Positions Expected to be Realized (Detail)	3 Months Ended
	Mar. 31, 2016 MMBTU bbl	Mar. 31, 2015 MMBTU bbl
Crude Oil [Member]
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), 2013 | bbl		(561,825)
Net (Short) Position (Bbls), 2014 | bbl	(1,100,000)	(561,922)
Net (Short) Position (Bbls), 2015 | bbl	0	0
Natural Gas [Member]
Derivative [Line Items]
Net Long (Short) Position (MMBtu), 2013 | MMBTU		(12,429,125)
Net Long (Short) Position (MMBtu), 2014 | MMBTU	(9,282,500)	(5,668,564)
Net Long (Short) Position (MMBtu), 2015 | MMBTU	(12,817,500)	(6,387,500)
Natural Gas Liquids [Member]
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), 2013 | bbl		4,231,200
Net (Short) Position (Bbls), 2014 | bbl	(180,000)	(813,267)
Net (Short) Position (Bbls), 2015 | bbl	0	0
Natural Gas Basis Swaps [Member]
Derivative [Line Items]
Net Long (Short) Position (MMBtu), 2013 | MMBTU		2,675,000
Net Long (Short) Position (MMBtu), 2014 | MMBTU	2,060,000	1,690,000
Net Long (Short) Position (MMBtu), 2015 | MMBTU	1,800,000	0