Risk Management and Hedging Activities - Schedule of Net Long or Short Positions Expected to be Realized (Detail)	12 Months Ended
	Dec. 31, 2015 MMBTU bbl	Dec. 31, 2014 MMBTU bbl
Crude Oil [Member]
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), 2013 | bbl		(745,695)
Net (Short) Position (Bbls), 2014 | bbl		(561,922)
Net (Short) Position (Bbls), 2015 | bbl	(1,408,672)	0
Net (Short) Position (Bbls), 2016 | bbl	0
Natural Gas [Member]
Derivative [Line Items]
Net Long (Short) Position (MMBtu), 2013 | MMBTU		(20,803,975)
Net Long (Short) Position (MMBtu), 2014 | MMBTU		(5,668,564)
Net Long (Short) Position (MMBtu), 2015 | MMBTU	(15,881,064)	(6,387,500)
Net Long (Short) Position (MMBtu), 2016 | MMBTU	(7,387,500)
Natural Gas Liquids [Member]
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), 2013 | bbl		5,573,570
Net (Short) Position (Bbls), 2014 | bbl		(813,267)
Net (Short) Position (Bbls), 2015 | bbl	(813,267)	0
Net (Short) Position (Bbls), 2016 | bbl	0
Natural Gas Basis Swaps [Member]
Derivative [Line Items]
Net Long (Short) Position (MMBtu), 2013 | MMBTU		2,640,000
Net Long (Short) Position (MMBtu), 2014 | MMBTU		1,690,000
Net Long (Short) Position (MMBtu), 2015 | MMBTU	2,665,000	0
Net Long (Short) Position (MMBtu), 2016 | MMBTU	1,800,000