Consolidated statements of operations (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues:
Commodity sales	$ 591,674	$ 509,503	$ 530,041
Gain (loss) from oil hedging activities	37,134	46,746	(27,452)
Other revenues	0	0	4,070
Total revenues	628,808	556,249	506,659
Costs and expenses:
Lease operating	139,771	130,960	121,420
Production taxes	33,266	32,003	34,321
Depreciation, depletion & amortization	192,426	169,307	146,083
Loss on impairment of other assets	3,490	2,000	0
General and administrative	53,883	49,812	42,056
Other expenses	0	0	3,448
Total costs and expenses	422,836	384,082	347,328
Operating income	205,972	172,167	159,331
Non-operating income (expense):
Interest expense	(96,876)	(98,402)	(96,720)
Non-hedge derivative (losses) gains	(21,635)	49,685	34,408
Loss on extinguishment of debt	0	(21,714)	(20,592)
Other income	1,075	504	1,545
Net non-operating expense	(117,436)	(69,927)	(81,359)
Income before income taxes	88,536	102,240	77,972
Income tax expense	32,849	37,837	35,924
Net income	$ 55,687	$ 64,403	$ 42,048