Condensed Statements of Operations (USD $) In Thousands, except Per Share data, 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	$ 274,715	$ 221,781	$ 541,487	$ 455,434
Electricity sales	9,513	5,860	17,102	11,840
Natural gas marketing	2,255	1,580	4,282	3,439
(Loss) gain on sale of assets	0	(163)	23	1,600
Interest and other income, net	374	645	849	1,392
TOTAL REVENUES	286,857	229,703	563,743	473,705
EXPENSES
Operating costs—oil and natural gas production	91,277	62,426	177,425	116,647
Operating costs- electricity generation	6,337	4,256	11,633	9,273
Production taxes	11,004	9,690	21,788	20,348
Depreciation, depletion & amortization			138,749	100,903
Natural gas marketing	2,198	1,387	4,076	3,164
General and administrative	19,430	17,965	41,708	35,706
Interest	24,879	20,789	49,566	40,893
Dry hole, abandonment, impairment and exploration	872	1,582	1,834	4,621
Impairment of oil and natural gas properties	0	38	2,467	66
Extinguishment of debt	0	41,526	0	41,526
Realized and unrealized gain on derivatives, net	(35,622)	(113,082)	(34,885)	(84,601)
TOTAL EXPENSES	190,647	99,058	414,362	288,546
Earnings before income taxes	96,210	130,645	149,381	185,159
Income tax provision	34,846	49,629	55,583	70,245
Net earnings	61,364	81,016	93,798	114,914
Basic net earnings per share (in dollars per share)	$ 1.11	$ 1.47	$ 1.69	$ 2.08
Diluted net earnings per share (in dollars per share)	$ 1.10	$ 1.46	$ 1.68	$ 2.07
Dividends per share (in dollars per share)	$ 0.08	$ 0.08	$ 0.16	$ 0.16
Oil and Natural Gas Properties, Buildings, and Equipment
EXPENSES
Depreciation, depletion & amortization	69,839	52,026	137,923	99,982
Electricity Generation
EXPENSES
Depreciation, depletion & amortization	$ 433	$ 455	$ 827	$ 921