Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating revenue:
Oil production										$ 715,104	$ 761,304	$ 663,958
Gas production										190,580	134,739	170,611
Natural gas liquids production										60,687	48,498	29,996
Other operational income										7,808	3,520	3,938
Derivative income, net											3,428	1,418
Total operating revenue	239,253		256,685	245,877	233,732	254,871	227,397	226,561	244,957	974,179	951,489	869,921
Operating expenses:
Lease operating expenses										201,153	215,003	175,881
Transportation, processing and gathering expenses										42,172	21,782	8,958
Production taxes										15,029	10,015	9,380
Depreciation, depletion, amortization										350,574	344,365	280,020
Accretion expense										33,575	33,331	30,764
Salaries, general and administrative										59,524	54,648	40,169
Franchise tax settlement	12,590									12,590
Incentive compensation expense										15,340	8,113	11,600
Other operational expenses										151	267	2,149
Derivative expense, net										2,090
Total operating expenses										732,198	687,524	558,921
Income (loss) from operations	37,206	[1]	62,422	69,525	72,828	78,397	44,485	56,156	84,927	241,981	263,965	311,000
Other (income) expenses:
Interest expense										32,837	30,375	9,289
Interest income										(1,695)	(600)	(420)
Other income										(2,799)	(1,805)	(1,942)
Loss on early extinguishment of debt	27,279									27,279	1,972	607
Total other (income) expenses										55,622	29,942	7,534
Income (loss) before taxes										186,359	234,023	303,466
Provision (benefit) for income taxes:
Current										(10,904)	15,022	(20,386)
Deferred										79,629	69,575	129,520
Total income taxes										68,725	84,597	109,134
Net income (loss)	1,752	[1],[2]	36,102	39,022	40,758	44,246	23,659	30,547	50,974	117,634	149,426	194,332
Comprehensive income (loss)										86,739	156,391	230,404
Parent [Member]
Operating revenue:
Oil production										30,475	26,149	5,675
Gas production										68,895	34,331	19,470
Natural gas liquids production										32,293	15,264
Other operational income										7,163	2,766	3,085
Total operating revenue										138,826	78,510	28,230
Operating expenses:
Lease operating expenses										14,680	19,914	6,632
Transportation, processing and gathering expenses										28,322	12,049
Production taxes										6,229	3,330	1,434
Depreciation, depletion, amortization										93,579	63,022	17,860
Accretion expense										372	561	15
Salaries, general and administrative										59,473	54,641	40,073
Franchise tax settlement										12,590
Incentive compensation expense										15,340	8,113	11,600
Other operational expenses										38	173	1,404
Total operating expenses										230,623	161,803	79,018
Income (loss) from operations										(91,797)	(83,293)	(50,788)
Other (income) expenses:
Interest expense										32,816	30,446	9,043
Interest income										(1,480)	(285)	(178)
Other income										(875)	(144)	(52)
Loss on early extinguishment of debt										27,279	1,972	607
(Income) loss from investment in subsidiaries										(214,983)	(223,555)	(232,751)
Total other (income) expenses										(157,243)	(191,566)	(223,331)
Income (loss) before taxes										65,446	108,273	172,543
Provision (benefit) for income taxes:
Current										(10,904)	15,022	(20,386)
Deferred										(41,284)	(56,175)	(1,403)
Total income taxes										(52,188)	(41,153)	(21,789)
Net income (loss)										117,634	149,426	194,332
Comprehensive income (loss)										86,739	156,391	230,404
Guarantor Subsidiary [Member]
Operating revenue:
Oil production										684,629	735,155	658,283
Gas production										121,685	100,408	151,141
Natural gas liquids production										28,394	33,234	29,996
Other operational income										645	397	249
Derivative income, net											3,428	1,418
Total operating revenue										835,353	872,622	841,087
Operating expenses:
Lease operating expenses										186,473	195,105	169,018
Transportation, processing and gathering expenses										13,850	9,733	8,958
Production taxes										8,800	6,685	7,946
Depreciation, depletion, amortization										256,995	281,152	261,326
Accretion expense										33,203	32,513	30,385
Salaries, general and administrative										5	7	94
Other operational expenses										113	94	745
Derivative expense, net										2,090
Total operating expenses										501,529	525,289	478,472
Income (loss) from operations										333,824	347,333	362,615
Other (income) expenses:
Interest expense										21	(71)	246
Interest income										(195)	(315)	(242)
Other income										(1,924)	(1,661)	(1,890)
(Income) loss from investment in subsidiaries											75	827
Total other (income) expenses										(2,098)	(1,972)	(1,059)
Income (loss) before taxes										335,922	349,305	363,674
Provision (benefit) for income taxes:
Deferred										120,913	125,750	130,923
Total income taxes										120,913	125,750	130,923
Net income (loss)										215,009	223,555	232,751
Comprehensive income (loss)										215,009	223,555	232,751
Non-Guarantor Subsidiaries [Member]
Operating revenue:
Other operational income											357	604
Total operating revenue											357	604
Operating expenses:
Lease operating expenses											(16)	231
Depreciation, depletion, amortization											191	834
Accretion expense											257	364
Salaries, general and administrative										46		2
Total operating expenses										46	432	1,431
Income (loss) from operations										(46)	(75)	(827)
Other (income) expenses:
Interest income										(20)
(Income) loss from investment in subsidiaries										26
Total other (income) expenses										6
Income (loss) before taxes										(52)	(75)	(827)
Provision (benefit) for income taxes:
Net income (loss)										(52)	(75)	(827)
Comprehensive income (loss)										(52)	(75)	(827)
Consolidation, Eliminations [Member]
Other (income) expenses:
(Income) loss from investment in subsidiaries										214,957	223,480	231,924
Total other (income) expenses										214,957	223,480	231,924
Income (loss) before taxes										(214,957)	(223,480)	(231,924)
Provision (benefit) for income taxes:
Net income (loss)										(214,957)	(223,480)	(231,924)
Comprehensive income (loss)										$ (214,957)	$ (223,480)	$ (231,924)

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

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