Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues
Oil and gas revenues	$ 344,706	$ 286,952	$ 1,030,735	$ 770,445
Well services and midstream revenues	23,953	18,546	59,821	37,939
Total revenues	368,659	305,498	1,090,556	808,384
Expenses
Lease operating expenses	44,361	21,831	124,903	59,586
Well services and midstream operating expenses	14,922	10,319	34,611	19,877
Marketing, transportation and gathering expenses	7,306	5,688	19,606	19,856
Production taxes	34,584	26,823	100,880	70,309
Depreciation, depletion and amortization	106,972	72,728	295,520	205,779
Exploration expenses	1,100	463	1,955	2,712
Impairment of oil and gas properties	1,439	56	2,243	762
General and administrative expenses	23,915	16,728	68,186	47,238
Total expenses	234,599	154,636	647,904	426,119
Gain on sale of properties	43	0	187,076	0
Operating income (loss)	134,103	150,862	629,728	382,265
Other income (expense)
Net gain (loss) on derivative instruments	103,426	(39,817)	20,253	(41,838)
Interest expense, net of capitalized interest	(39,420)	(22,854)	(118,568)	(65,429)
Other income (expense)	(38)	23	250	1,097
Total other income (expense)	63,968	(62,648)	(98,065)	(106,170)
Income before income taxes	198,071	88,214	531,663	276,095
Income tax benefit (expense)	(76,484)	(33,715)	(201,290)	(102,626)
Net income	121,587	54,499	330,373	173,469
Parent/Issuer [Member]
Expenses
General and administrative expenses	6,373	3,746	17,790	10,146
Total expenses	6,373	3,746	17,790	10,146
Operating income (loss)	(6,373)	(3,746)	(17,790)	(10,146)
Other income (expense)
Equity in earnings in subsidiaries	148,357	70,118	410,775	218,869
Interest expense, net of capitalized interest	(36,724)	(21,277)	(110,853)	(61,955)
Other income (expense)		15	3	(348)
Total other income (expense)	111,633	48,856	299,925	156,566
Income before income taxes	105,260	45,110	282,135	146,420
Income tax benefit (expense)	16,327	9,389	48,238	27,049
Net income	121,587	54,499	330,373	173,469
Combined Guarantor Subsidiaries [Member]
Revenues
Oil and gas revenues	344,706	286,952	1,030,735	770,445
Well services and midstream revenues	23,953	18,546	59,821	37,939
Total revenues	368,659	305,498	1,090,556	808,384
Expenses
Lease operating expenses	44,361	21,831	124,903	59,586
Well services and midstream operating expenses	14,922	10,319	34,611	19,877
Marketing, transportation and gathering expenses	7,306	5,688	19,606	19,856
Production taxes	34,584	26,823	100,880	70,309
Depreciation, depletion and amortization	106,972	72,728	295,520	205,779
Exploration expenses	1,100	463	1,955	2,712
Impairment of oil and gas properties	1,439	56	2,243	762
General and administrative expenses	17,542	12,982	50,396	37,092
Total expenses	228,226	150,890	630,114	415,973
Gain on sale of properties	43		187,076
Operating income (loss)	140,476	154,608	647,518	392,411
Other income (expense)
Net gain (loss) on derivative instruments	103,426	(39,817)	20,253	(41,838)
Interest expense, net of capitalized interest	(2,696)	(1,577)	(7,715)	(3,474)
Other income (expense)	(38)	8	247	1,445
Total other income (expense)	100,692	(41,386)	12,785	(43,867)
Income before income taxes	241,168	113,222	660,303	348,544
Income tax benefit (expense)	(92,811)	(43,104)	(249,528)	(129,675)
Net income	148,357	70,118	410,775	218,869
Intercompany Eliminations [Member]
Other income (expense)
Equity in earnings in subsidiaries	(148,357)	(70,118)	(410,775)	(218,869)
Total other income (expense)	(148,357)	(70,118)	(410,775)	(218,869)
Income before income taxes	(148,357)	(70,118)	(410,775)	(218,869)
Net income	$ (148,357)	$ (70,118)	$ (410,775)	$ (218,869)