Guarantor Financial Statements - Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended											12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating revenue:
Oil production												$ 516,104	$ 715,104	$ 761,304
Natural gas production												166,494	190,580	134,739
Natural gas liquids production												85,642	60,687	48,498
Other operational income												7,951	7,808	3,520
Derivative income, net												19,351		3,428
Total operating revenue	184,780		183,213		207,046	223,830	239,253		256,685	245,877	233,732	795,542	974,179	951,489
Operating expenses:
Lease operating expenses												176,495	201,153	215,003
Transportation, processing and gathering expenses												64,951	42,172	21,782
Production taxes												12,151	15,029	10,015
Depreciation, depletion, amortization												340,006	350,574	344,365
Write-down of oil and gas properties	304,062		47,130									351,192
Accretion expense												28,411	33,575	33,331
Salaries, general and administrative												66,451	59,524	54,648
Franchise tax settlement							12,590						12,590
Incentive compensation expense												10,361	15,340	8,113
Other operational expenses												862	151	267
Derivative expense, net													2,090
Total operating expenses												1,050,880	732,198	687,524
Income (loss) from operations	(286,147)	[1]	(34,356)	[2]	16,613	48,552	37,206	[3]	62,422	69,525	72,828	(255,338)	241,981	263,965
Other (income) expenses:
Interest expense												38,855	32,837	30,375
Interest income												(574)	(1,695)	(600)
Other income												(2,332)	(2,799)	(1,805)
Other expense												274
Loss on early extinguishment of debt							27,279						27,279	1,972
Total other (income) expenses												36,223	55,622	29,942
Income (loss) before taxes												(291,561)	186,359	234,023
Provision (benefit) for income taxes:
Current												159	(10,904)	15,022
Deferred												(102,177)	79,629	69,575
Total income taxes												(102,018)	68,725	84,597
Net income (loss)	(190,515)	[1]	(29,415)	[2]	4,444	25,943	1,752	[3],[4]	36,102	39,022	40,758	(189,543)	117,634	149,426
Comprehensive income (loss)												(104,166)	86,739	156,391
Parent [Member]
Operating revenue:
Oil production												29,701	30,475	26,149
Natural gas production												86,812	68,895	34,331
Natural gas liquids production												61,200	32,293	15,264
Other operational income												7,551	7,163	2,766
Total operating revenue												185,264	138,826	78,510
Operating expenses:
Lease operating expenses												18,719	14,680	19,914
Transportation, processing and gathering expenses												53,028	28,322	12,049
Production taxes												8,324	6,229	3,330
Depreciation, depletion, amortization												138,313	93,579	63,022
Write-down of oil and gas properties												351,192
Accretion expense												230	372	561
Salaries, general and administrative												66,430	59,473	54,641
Franchise tax settlement													12,590
Incentive compensation expense												10,361	15,340	8,113
Other operational expenses												669	38	173
Total operating expenses												647,266	230,623	161,803
Income (loss) from operations												(462,002)	(91,797)	(83,293)
Other (income) expenses:
Interest expense												38,810	32,816	30,446
Interest income												(333)	(1,480)	(285)
Other income												(836)	(875)	(144)
Other expense												274
Loss on early extinguishment of debt													27,279	1,972
(Income) loss from investment in subsidiaries												(133,336)	(214,983)	(223,555)
Total other (income) expenses												(95,421)	(157,243)	(191,566)
Income (loss) before taxes												(366,581)	65,446	108,273
Provision (benefit) for income taxes:
Current												159	(10,904)	15,022
Deferred												(177,197)	(41,284)	(56,175)
Total income taxes												(177,038)	(52,188)	(41,153)
Net income (loss)												(189,543)	117,634	149,426
Comprehensive income (loss)												(104,166)	86,739	156,391
Guarantor Subsidiary [Member]
Operating revenue:
Oil production												486,403	684,629	735,155
Natural gas production												79,682	121,685	100,408
Natural gas liquids production												24,442	28,394	33,234
Other operational income												400	645	397
Derivative income, net												19,351		3,428
Total operating revenue												610,278	835,353	872,622
Operating expenses:
Lease operating expenses												157,776	186,473	195,105
Transportation, processing and gathering expenses												11,923	13,850	9,733
Production taxes												3,827	8,800	6,685
Depreciation, depletion, amortization												201,693	256,995	281,152
Accretion expense												28,181	33,203	32,513
Salaries, general and administrative												4	5	7
Other operational expenses												193	113	94
Derivative expense, net													2,090
Total operating expenses												403,597	501,529	525,289
Income (loss) from operations												206,681	333,824	347,333
Other (income) expenses:
Interest expense												45	21	(71)
Interest income												(192)	(195)	(315)
Other income												(1,496)	(1,924)	(1,661)
(Income) loss from investment in subsidiaries														75
Total other (income) expenses												(1,643)	(2,098)	(1,972)
Income (loss) before taxes												208,324	335,922	349,305
Provision (benefit) for income taxes:
Deferred												75,020	120,913	125,750
Total income taxes												75,020	120,913	125,750
Net income (loss)												133,304	215,009	223,555
Comprehensive income (loss)												133,304	215,009	223,555
Non-Guarantor Subsidiaries [Member]
Operating revenue:
Other operational income														357
Total operating revenue														357
Operating expenses:
Lease operating expenses														(16)
Depreciation, depletion, amortization														191
Accretion expense														257
Salaries, general and administrative												17	46
Total operating expenses												17	46	432
Income (loss) from operations												(17)	(46)	(75)
Other (income) expenses:
Interest income												(49)	(20)
(Income) loss from investment in subsidiaries												(32)	26
Total other (income) expenses												(81)	6
Income (loss) before taxes												64	(52)	(75)
Provision (benefit) for income taxes:
Net income (loss)												64	(52)	(75)
Comprehensive income (loss)												64	(52)	(75)
Eliminations [Member]
Other (income) expenses:
(Income) loss from investment in subsidiaries												133,368	214,957	223,480
Total other (income) expenses												133,368	214,957	223,480
Income (loss) before taxes												(133,368)	(214,957)	(223,480)
Provision (benefit) for income taxes:
Net income (loss)												(133,368)	(214,957)	(223,480)
Comprehensive income (loss)												$ (133,368)	$ (214,957)	$ (223,480)

[1] Includes a write-down of oil and gas properties of $304,062 before income tax effect ($194,600 net of income tax effect).

[2] Includes a write-down of oil and gas properties of $47,130 before income tax effect ($30,163 net of income tax effect).

[3] Includes franchise tax settlement of $12,590 before income tax effect ($8,058 net of income tax effect).

[4] Includes loss on early extinguishment of debt of $27,279 before income tax effect ($17,459 net of income tax effect).