Condensed Consolidated Statement of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating revenue:
Oil production	$ 182,181	$ 175,357	$ 383,939	$ 327,352
Gas production	28,146	47,884	57,003	89,044
Natural gas liquids production	9,866	10,231	23,318	16,230
Other operational income	952	864	1,842	1,749
Derivative income, net	5,416	1,398	4,931
Total operating revenue	226,561	235,734	471,033	434,375
Operating expenses:
Lease operating expenses	51,555	45,608	96,035	83,895
Transportation, processing and gathering expenses	5,492	2,728	9,149	4,548
Other operational expenses	71	136	113	798
Production taxes	2,358	1,801	5,736	4,336
Depreciation, depletion and amortization	87,133	72,646	171,708	140,315
Accretion expense	8,255	7,717	16,521	15,434
Salaries, general and administrative expenses	13,143	10,610	26,848	22,343
Incentive compensation expense	2,398	2,333	3,840	5,017
Derivative expense, net				782
Total operating expenses	170,405	143,579	329,950	277,468
Income from operations	56,156	92,155	141,083	156,907
Other (income) expenses:
Interest expense	7,684	1,980	13,415	5,091
Interest income	(79)	(53)	(110)	(147)
Other income	(366)	(563)	(786)	(1,127)
Loss on early extinguishment of debt		607		607
Other expense		69		193
Total other expenses	7,239	2,040	12,519	4,617
Net income before income taxes	48,917	90,115	128,564	152,290
Provision (benefit) for income taxes:
Current	(665)	(2,362)	569	(2,362)
Deferred	19,035	35,281	46,474	57,664
Total income taxes	18,370	32,919	47,043	55,302
Net income	$ 30,547	$ 57,196	$ 81,521	$ 96,988
Basic earnings per share	$ 0.62	$ 1.17	$ 1.65	$ 1.98
Diluted earnings per share	$ 0.62	$ 1.17	$ 1.65	$ 1.98
Average shares outstanding	48,303	47,961	48,279	47,930
Average shares outstanding assuming dilution	48,344	48,006	48,322	47,973