Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
REVENUES
Sales of oil and natural gas	$ 870,773		$ 619,608		$ 500,532
Sales of electricity	34,953		34,740		36,065
Natural gas marketing	13,832		22,162		22,806
Settlement of Flying J bankruptcy claim	0		21,992		0
Gain on sale of assets	0		0		826
Interest and other income, net	1,784		3,300		1,810
TOTAL REVENUES	921,342		701,802		562,039
EXPENSES
Operating costs- oil and natural gas production	237,476		190,218		156,612
Operating costs- electricity generation	25,690		31,295		31,400
Production taxes	33,617		22,999		18,144
Depreciation, depletion & amortization- oil and natural gas production	213,859		179,432		139,919
Depreciation, depletion & amortization- electricity generation	1,963		3,225		3,681
Natural gas marketing	13,038		19,896		21,231
General and administrative	61,727		52,846		49,237
Interest	72,807		66,541		49,923
Extinguishment of debt	15,544		573		10,823
Realized and unrealized (gain) loss on derivatives, net	(13,908)		31,847		7,756
Gain on purchase	(1,046)		0		0
Transaction costs on acquisitions	0		2,635		0
Impairment of oil and natural gas properties	625,564		0		1,017
Dry hole, abandonment, impairment and exploration	5,302		2,311		4,408
Bad debt recovery	0		(38,508)		0
TOTAL EXPENSES	1,291,633		565,310		494,151
(Loss) earnings from continuing operations before income taxes	(370,291)		136,492		67,888
Income tax (benefit) provision	(142,228)		53,968		20,664
Net (loss) earnings from continuing operations	(228,063)		82,524		47,224
Net earnings from discontinued operations	0		0		6,806
Net (loss) earnings	$ (228,063)		$ 82,524		$ 54,030
Basic net (loss) earnings per share from continuing operations (in dollars per share)	$ (4.21)		$ 1.54		$ 1.03
Basic net earnings per share from discontinued operations (in dollars per share)	$ 0.00		$ 0.00		$ 0.15
Basic net (loss) earnings per share (in dollars per share)	$ (4.21)	[1]	$ 1.54	[1]	$ 1.18
Diluted net (loss) earnings per share from continuing operations (in dollars per share)	$ (4.21)		$ 1.52		$ 1.02
Diluted net earnings per share from discontinued operations (in dollars per share)	$ 0.00		$ 0.00		$ 0.15
Diluted net (loss) earnings per share (in dollars per share)	$ (4.21)	[1]	$ 1.52	[1]	$ 1.17
Dividends per share (in dollars per share)	$ 0.31		$ 0.30		$ 0.30

[1] The sum of the individual quarterly net (loss) earnings per common share amounts may not agree with year-to-date net (loss) earnings per common share as each quarterly computation is based on the weighted-average number of common shares outstanding during that period. Potentially dilutive securities were included in the computation of diluted net (loss) earnings per common share for each quarter in which the Company reported net