Supplemental Crude Oil and Natural Gas Information - Schedule of Proved Crude Oil and Natural Gas Reserves (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015 $ / Barrels	Dec. 31, 2015 MBoe	Dec. 31, 2015 MBbls	Dec. 31, 2015 MMcf	Dec. 31, 2014 $ / Barrels MBoe MBbls MMcf	Dec. 31, 2013 MBoe MBbls MMcf
Reserve Quantities [Line Items]
Percentage of discounted future net cash flows prepared by external reserve engineers	99.00%					99.00%	99.00%
Changes in Proved Reserves [Roll Forward]
Proved reserves at beginning of period, Total			1,351,091			1,084,125	784,677
Revisions of previous estimates, Total			(297,198)			(107,949)	(96,054)
Extensions, discoveries and other additions, Total			253,173			440,621	444,654
Production, Total			(80,926)			(63,579)	(49,610)
Sales of minerals in place, Total			(329)			(3,227)	0
Purchases of minerals in place, Total			0			1,100	458
Proved reserves at end of period, Total			1,225,811			1,351,091	1,084,125
Percent of proved crude oil reserve estimates prepared by external reserve engineers	99.00%
Percent of proved natural gas reserve estimates prepared by external reserve engineers	97.00%
Natural Gas [Member]
Reserve Quantities [Line Items]
Twelve month average SEC price | $ / Barrels		2.58				4.35
Changes in Proved Reserves [Roll Forward]
Proved reserves at beginning of period | MMcf					2,908,386	2,078,020	1,341,084
Revisions of previous estimates | MMcf					(302,143)	(244,783)	(241,623)
Extensions, discoveries and other additions | MMcf					710,453	1,206,569	1,065,870
Production | MMcf					(164,454)	(114,295)	(87,730)
Sales of minerals in place | MMcf					(456)	(18,623)	0
Purchases of minerals in place | MMcf					0	1,498	419
Proved reserves at end of period | MMcf					3,151,786	2,908,386	2,078,020
Crude Oil [Member]
Reserve Quantities [Line Items]
Twelve month average SEC price | $ / Barrels		50.28				94.99
Changes in Proved Reserves [Roll Forward]
Proved reserves at beginning of period | MBbls				866,360		737,788	561,163
Revisions of previous estimates | MBbls				(246,840)		(67,151)	(55,783)
Extensions, discoveries and other additions | MBbls				134,764		239,526	267,009
Production | MBbls				(53,517)		(44,530)	(34,989)
Sales of minerals in place | MBbls				(253)		(123)	0
Purchases of minerals in place | MBbls				0		850	388
Proved reserves at end of period | MBbls				700,514		866,360	737,788
Northwest Cana [Member]
Changes in Proved Reserves [Roll Forward]
Extensions, discoveries and other additions				20,000	222,000
Extensions, discoveries and other additions, Total			57,000