Guarantor Financial Statements - Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating revenue:
Oil production	$ 138,289	$ 186,925
Gas production	56,362	36,822
Natural gas liquids production	27,970	9,178
Other operational income	1,209	807
Total operating revenue	223,830	233,732
Operating expenses:
Lease operating expenses	46,903	53,044
Transportation, processing and gathering expenses	14,626	5,397
Production taxes	3,062	2,089
Depreciation, depletion, amortization	82,646	75,435
Accretion expense	7,555	8,263
Salaries, general and administrative	16,329	13,952
Incentive compensation expense	3,134	1,431
Other operational expenses	424	72
Derivative expense, net	599	1,221
Total operating expenses	175,278	160,904
Income (loss) from operations	48,552	72,828
Other (income) expenses:
Interest expense	8,357	9,635
Interest income	(143)	(117)
Other income	(707)	(726)
Income from investment in subsidiaries
Total other (income) expenses	7,507	8,792
Income before taxes	41,045	64,036
Provision (benefit) for income taxes:
Current		(3,746)
Deferred	15,102	27,024
Total income taxes	15,102	23,278
Net income	25,943	40,758
Comprehensive income	18,854	22,417
Parent [Member]
Operating revenue:
Oil production	6,636	5,343
Gas production	28,839	7,198
Natural gas liquids production	18,254	2,299
Other operational income	1,042	649
Total operating revenue	54,771	15,489
Operating expenses:
Lease operating expenses	4,013	2,291
Transportation, processing and gathering expenses	10,317	2,052
Production taxes	1,681	867
Depreciation, depletion, amortization	28,055	10,191
Accretion expense	68	93
Salaries, general and administrative	16,325	13,948
Incentive compensation expense	3,134	1,431
Other operational expenses	394	50
Total operating expenses	63,987	30,923
Income (loss) from operations	(9,216)	(15,434)
Other (income) expenses:
Interest expense	8,353	9,627
Interest income	(79)	(80)
Other income	(181)	(224)
Income from investment in subsidiaries	(37,345)	(56,828)
Total other (income) expenses	(29,252)	(47,505)
Income before taxes	20,036	32,071
Provision (benefit) for income taxes:
Current		(3,746)
Deferred	(5,907)	(4,941)
Total income taxes	(5,907)	(8,687)
Net income	25,943	40,758
Comprehensive income	18,854	22,417
Guarantor Subsidiary [Member]
Operating revenue:
Oil production	131,653	181,582
Gas production	27,523	29,624
Natural gas liquids production	9,716	6,879
Other operational income	167	158
Total operating revenue	169,059	218,243
Operating expenses:
Lease operating expenses	42,890	50,753
Transportation, processing and gathering expenses	4,309	3,345
Production taxes	1,381	1,222
Depreciation, depletion, amortization	54,591	65,244
Accretion expense	7,487	8,170
Salaries, general and administrative	2	4
Other operational expenses	30	22
Derivative expense, net	599	1,221
Total operating expenses	111,289	129,981
Income (loss) from operations	57,770	88,262
Other (income) expenses:
Interest expense	4	8
Interest income	(58)	(37)
Other income	(526)	(502)
Total other (income) expenses	(580)	(531)
Income before taxes	58,350	88,793
Provision (benefit) for income taxes:
Deferred	21,009	31,965
Total income taxes	21,009	31,965
Net income	37,341	56,828
Comprehensive income	37,341	56,828
Non-Guarantor Subsidiaries [Member]
Operating revenue:
Other operational income
Total operating revenue
Operating expenses:
Lease operating expenses
Depreciation, depletion, amortization
Accretion expense
Salaries, general and administrative	2
Total operating expenses	2
Income (loss) from operations	(2)
Other (income) expenses:
Interest income	(6)
Income from investment in subsidiaries	(4)
Total other (income) expenses	(10)
Income before taxes	8
Provision (benefit) for income taxes:
Net income	8
Comprehensive income	8
Consolidation, Eliminations [Member]
Other (income) expenses:
Income from investment in subsidiaries	37,349	56,828
Total other (income) expenses	37,349	56,828
Income before taxes	(37,349)	(56,828)
Provision (benefit) for income taxes:
Net income	(37,349)	(56,828)
Comprehensive income	$ (37,349)	$ (56,828)