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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues
Oil and gas revenues	$ 286,952	$ 178,748	$ 770,445	$ 461,857
Well services and midstream revenues	18,546	5,963	37,939	10,484
Total revenues	305,498	184,711	808,384	472,341
Expenses
Lease operating expenses	21,831	16,134	59,586	37,979
Well services and midstream operating expenses	10,319	5,420	19,877	7,104
Marketing, transportation and gathering expenses	5,688	2,744	19,856	7,283
Production taxes	26,823	16,433	70,309	43,419
Depreciation, depletion and amortization	72,728	57,684	205,779	140,783
Exploration expenses	463	336	2,712	3,171
Impairment of oil and gas properties	56	36	762	2,607
General and administrative expenses	16,728	13,886	47,238	39,622
Total expenses	154,636	112,673	426,119	281,968
Operating income (loss)	150,862	72,038	382,265	190,373
Other income (expense)
Equity in earnings in subsidiaries
Net gain (loss) on derivative instruments	(39,817)	(22,441)	(41,838)	33,568
Interest expense, net of capitalized interest	(22,854)	(20,979)	(65,429)	(48,952)
Other income	23	1,147	1,097	2,521
Total other income (expense)	(62,648)	(42,273)	(106,170)	(12,863)
Income before income taxes	88,214	29,765	276,095	177,510
Income tax benefit (expense)	(33,715)	(11,451)	(102,626)	(66,712)
Net income	54,499	18,314	173,469	110,798
Parent/Issuer [Member]
Expenses
General and administrative expenses	3,746	2,988	10,146	8,078
Total expenses	3,746	2,988	10,146	8,078
Operating income (loss)	(3,746)	(2,988)	(10,146)	(8,078)
Other income (expense)
Equity in earnings in subsidiaries	70,118	32,735	218,869	145,021
Interest expense, net of capitalized interest	(21,277)	(20,307)	(61,955)	(47,136)
Other income	15	238	(348)	533
Total other income (expense)	48,856	12,666	156,566	98,418
Income before income taxes	45,110	9,678	146,420	90,340
Income tax benefit (expense)	9,389	8,636	27,049	20,458
Net income	54,499	18,314	173,469	110,798
Combined Guarantor Subsidiaries [Member]
Revenues
Oil and gas revenues	286,952	178,748	770,445	461,857
Well services and midstream revenues	18,546	5,963	37,939	10,484
Total revenues	305,498	184,711	808,384	472,341
Expenses
Lease operating expenses	21,831	16,134	59,586	37,979
Well services and midstream operating expenses	10,319	5,420	19,877	7,104
Marketing, transportation and gathering expenses	5,688	2,744	19,856	7,283
Production taxes	26,823	16,433	70,309	43,419
Depreciation, depletion and amortization	72,728	57,684	205,779	140,783
Exploration expenses	463	336	2,712	3,171
Impairment of oil and gas properties	56	36	762	2,607
General and administrative expenses	12,982	10,898	37,092	31,544
Total expenses	150,890	109,685	415,973	273,890
Operating income (loss)	154,608	75,026	392,411	198,451
Other income (expense)
Equity in earnings in subsidiaries
Net gain (loss) on derivative instruments	(39,817)	(22,441)	(41,838)	33,568
Interest expense, net of capitalized interest	(1,577)	(672)	(3,474)	(1,816)
Other income	8	909	1,445	1,988
Total other income (expense)	(41,386)	(22,204)	(43,867)	33,740
Income before income taxes	113,222	52,822	348,544	232,191
Income tax benefit (expense)	(43,104)	(20,087)	(129,675)	(87,170)
Net income	70,118	32,735	218,869	145,021
Intercompany Eliminations [Member]
Other income (expense)
Equity in earnings in subsidiaries	(70,118)	(32,735)	(218,869)	(145,021)
Total other income (expense)	(70,118)	(32,735)	(218,869)	(145,021)
Income before income taxes	(70,118)	(32,735)	(218,869)	(145,021)
Net income	$ (70,118)	$ (32,735)	$ (218,869)	$ (145,021)