Guarantor Financial Statements - Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating revenue:
Oil production	$ 142,393	$ 184,498	$ 280,682	$ 371,423
Gas production	46,667	47,832	103,029	84,654
Natural gas liquids production	15,936	11,200	43,906	20,378
Other operational income	2,050	979	3,047	1,786
Derivate income, net		1,368		147
Total operating revenue	207,046	245,877	430,664	478,388
Operating expenses:
Lease operating expenses	49,454	50,517	96,357	103,561
Transportation, processing and gathering expenses	14,098	8,896	28,724	14,293
Production taxes	3,257	4,091	6,319	6,180
Depreciation, depletion, amortization	92,835	87,209	175,481	162,644
Accretion expense	7,733	8,318	15,288	16,581
Salaries, general and administrative	16,637	15,198	32,966	29,150
Incentive compensation expense	3,903	2,050	7,037	3,481
Other operational expenses		73	212	145
Derivative expense, net	2,516		3,115
Total operating expenses	190,433	176,352	365,499	336,035
Income (loss) from operations	16,613	69,525	65,165	142,353
Other (income) expenses:
Interest expense	9,913	8,895	18,270	18,530
Interest income	(193)	(115)	(336)	(232)
Other income	(722)	(682)	(1,429)	(1,408)
Other expense	179		179
Total other (income) expenses	9,177	8,098	16,684	16,890
Income (loss) before taxes	7,436	61,427	48,481	125,463
Provision (benefit) for income taxes:
Current		(6,993)		(10,739)
Deferred	2,992	29,398	18,094	56,422
Total income taxes	2,992	22,405	18,094	45,683
Net income	4,444	39,022	30,387	79,780
Comprehensive income	(4,566)	53,060	14,288	75,477
Parent [Member]
Operating revenue:
Oil production	5,854	8,378	12,490	13,721
Gas production	20,800	20,071	49,639	27,269
Natural gas liquids production	10,219	6,378	28,473	8,677
Other operational income	1,880	790	2,704	1,439
Total operating revenue	38,753	35,617	93,306	51,106
Operating expenses:
Lease operating expenses	5,046	3,425	9,059	5,716
Transportation, processing and gathering expenses	10,456	5,729	20,773	7,781
Production taxes	1,903	1,320	3,584	2,187
Depreciation, depletion, amortization	30,385	25,088	58,440	35,279
Accretion expense	61	93	129	186
Salaries, general and administrative	16,639	15,150	32,964	29,098
Incentive compensation expense	3,903	2,050	7,037	3,481
Other operational expenses		51	176	101
Total operating expenses	68,393	52,906	132,162	83,829
Income (loss) from operations	(29,640)	(17,289)	(38,856)	(32,723)
Other (income) expenses:
Interest expense	9,880	8,882	18,233	18,509
Interest income	(146)	(70)	(225)	(150)
Other income	(192)	(217)	(373)	(441)
Other expense	179		179
(Income) loss from investment in subsidiaries	(29,947)	(55,893)	(67,292)	(112,721)
Total other (income) expenses	(20,226)	(47,298)	(49,478)	(94,803)
Income (loss) before taxes	(9,414)	30,009	10,622	62,080
Provision (benefit) for income taxes:
Current		(6,993)		(10,739)
Deferred	(13,858)	(2,020)	(19,765)	(6,961)
Total income taxes	(13,858)	(9,013)	(19,765)	(17,700)
Net income	4,444	39,022	30,387	79,780
Comprehensive income	(4,566)	53,060	14,288	75,477
Guarantor Subsidiary [Member]
Operating revenue:
Oil production	136,539	176,120	268,192	357,702
Gas production	25,867	27,761	53,390	57,385
Natural gas liquids production	5,717	4,822	15,433	11,701
Other operational income	170	189	343	347
Derivate income, net		1,368		147
Total operating revenue	168,293	210,260	337,358	427,282
Operating expenses:
Lease operating expenses	44,408	47,092	87,298	97,845
Transportation, processing and gathering expenses	3,642	3,167	7,951	6,512
Production taxes	1,354	2,771	2,735	3,993
Depreciation, depletion, amortization	62,450	62,121	117,041	127,365
Accretion expense	7,672	8,225	15,159	16,395
Salaries, general and administrative			2	4
Other operational expenses		22	36	44
Derivative expense, net	2,516		3,115
Total operating expenses	122,042	123,398	233,337	252,158
Income (loss) from operations	46,251	86,862	104,021	175,124
Other (income) expenses:
Interest expense	33	13	37	21
Interest income	(41)	(38)	(99)	(75)
Other income	(530)	(465)	(1,056)	(967)
Total other (income) expenses	(538)	(490)	(1,118)	(1,021)
Income (loss) before taxes	46,789	87,352	105,139	176,145
Provision (benefit) for income taxes:
Deferred	16,850	31,418	37,859	63,383
Total income taxes	16,850	31,418	37,859	63,383
Net income	29,939	55,934	67,280	112,762
Comprehensive income	29,939	55,934	67,280	112,762
Non-Guarantor Subsidiaries [Member]
Operating expenses:
Salaries, general and administrative	(2)	48		48
Total operating expenses	(2)	48		48
Income (loss) from operations	2	(48)		(48)
Other (income) expenses:
Interest income	(6)	(7)	(12)	(7)
(Income) loss from investment in subsidiaries	(8)	39	(12)	39
Total other (income) expenses	(14)	32	(24)	32
Income (loss) before taxes	16	(80)	24	(80)
Provision (benefit) for income taxes:
Net income	16	(80)	24	(80)
Comprehensive income	16	(80)	24	(80)
Consolidation, Eliminations [Member]
Other (income) expenses:
(Income) loss from investment in subsidiaries	29,955	55,854	67,304	112,682
Total other (income) expenses	29,955	55,854	67,304	112,682
Income (loss) before taxes	(29,955)	(55,854)	(67,304)	(112,682)
Provision (benefit) for income taxes:
Net income	(29,955)	(55,854)	(67,304)	(112,682)
Comprehensive income	$ (29,955)	$ (55,854)	$ (67,304)	$ (112,682)