Derivative Instruments - Summary of Outstanding Contracts with Respect to Crude Oil (Detail)	9 Months Ended										9 Months Ended										2 Months Ended		2 Months Ended		2 Months Ended				2 Months Ended
	Sep. 30, 2014 bbl	Sep. 30, 2014 ICE Brent [Member] October 2014 to December 2014 Swaps [Member] bbl	Sep. 30, 2014 ICE Brent [Member] October 2014 to December 2014 Collars [Member] bbl	Sep. 30, 2014 ICE Brent [Member] January 2015 - December 2015 Swaps [Member] bbl	Sep. 30, 2014 ICE Brent [Member] January 2015 to December 2015 Collars [Member] bbl	Sep. 30, 2014 ICE Brent [Member] January 2016 to December 2016 Swaps [Member] bbl	Sep. 30, 2014 ICE Brent [Member] Minimum [Member] October 2014 to December 2014 Collars [Member]	Sep. 30, 2014 ICE Brent [Member] Minimum [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 ICE Brent [Member] Maximum [Member] October 2014 to December 2014 Collars [Member]	Sep. 30, 2014 ICE Brent [Member] Maximum [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 West Texas Intermediate [Member] October 2014 to December 2014 Swaps [Member] bbl	Sep. 30, 2014 West Texas Intermediate [Member] January 2015 - December 2015 Swaps [Member]	Sep. 30, 2014 West Texas Intermediate [Member] Minimum [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 West Texas Intermediate [Member] Maximum [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 Natural Gas [Member] October 2014 to December 2014 Swaps [Member]	Sep. 30, 2014 Natural Gas [Member] January 2015 - December 2015 Swaps [Member]	Sep. 30, 2014 Natural Gas [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 Natural Gas [Member] January 2016 to December 2016 Swaps [Member]	Sep. 30, 2014 Natural Gas [Member] Minimum [Member] January 2015 to December 2015 Collars [Member]	Sep. 30, 2014 Natural Gas [Member] Maximum [Member] January 2015 to December 2015 Collars [Member]	Dec. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Call Option January 2015 to December 2015 [Member] bbl	Oct. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Call Option January 2015 to December 2015 [Member]	Dec. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Call Option January 2016 to December 2016 [Member] bbl	Oct. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Call Option January 2016 to December 2016 [Member]	Dec. 31, 2014 Subsequent Event [Member] ICE Brent [Member] October 2014 to December 2014 Collars [Member] bbl	Oct. 31, 2014 Subsequent Event [Member] ICE Brent [Member] October 2014 to December 2014 Collars [Member]	Oct. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Minimum [Member] October 2014 to December 2014 Collars [Member]	Oct. 31, 2014 Subsequent Event [Member] ICE Brent [Member] Maximum [Member] October 2014 to December 2014 Collars [Member]	Dec. 31, 2014 Subsequent Event [Member] West Texas Intermediate [Member] Call Option January 2015 to December 2015 [Member] bbl	Oct. 31, 2014 Subsequent Event [Member] West Texas Intermediate [Member] Call Option January 2015 to December 2015 [Member]	Oct. 31, 2014 Subsequent Event [Member] West Texas Intermediate [Member] Minimum [Member] Call Option January 2015 to December 2015 [Member]	Oct. 31, 2014 Subsequent Event [Member] West Texas Intermediate [Member] Maximum [Member] Call Option January 2015 to December 2015 [Member]
Derivative [Line Items]
Oil Production Derivative Volume	4,380,000	4,508,000	552,000	24,637,500	730,000	1,464,000					3,335,000										730,000		1,464,000		366,000				4,380,000
Derivative, Average Price Risk Option Strike Price																						107.4		107.7						98.36
Swaps Weighted Average Price		103.29		100.85							96.22				4.20	4.27		4.27
Derivative, Floor Price							90.00	95.00	95.00	95.00			87.00	87.00					3.50	3.75							90.00	95.00
Floors, Weighted Average Price			90.83		95.00	90.00						87.00					3.69									90.83
Derivative, Cap Price							104.70	107.40	108.85	107.40			95.85	103.75					4.89	5.48							104.70	108.85
Derivative, Price Risk Option Strike Price																															95.85	103.75
Ceilings, Weighted Average Price			107.13		107.40	107.70						98.36					5.04									107.13