Consolidated Statements Of Operations (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues:
Oil and natural gas sales	$ 144,353	$ 115,448	$ 271,865	$ 243,237
Gain from oil hedging activities	9,509	11,886	19,512	24,309
Total revenues	153,862	127,334	291,377	267,546
Costs and expenses:
Lease operating	32,949	32,719	66,926	63,668
Production taxes	8,588	7,220	16,468	15,510
Depreciation, depletion and amortization	47,941	38,454	91,857	75,386
General and administrative	11,553	12,838	25,561	26,287
Total costs and expenses	101,031	91,231	200,812	180,851
Operating income	52,831	36,103	90,565	86,695
Non-operating income (expense):
Interest expense	(24,200)	(24,423)	(48,491)	(48,579)
Non-hedge derivative gains	32,892	72,528	17,346	62,065
Loss on extinguishment of debt	0	(21,696)	0	(21,696)
Other income, net	187	127	413	132
Net non-operating income (expense)	8,879	26,536	(30,732)	(8,078)
Income before income taxes	61,710	62,639	59,833	78,617
Income tax expense	22,810	22,176	22,123	28,372
Net income	$ 38,900	$ 40,463	$ 37,710	$ 50,245