Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
REVENUES
Oil and natural gas sales	$ 937,261		$ 870,773		$ 619,608
Electricity sales	29,940		34,953		34,740
Natural gas marketing	7,631		13,832		22,162
Settlement of Flying J bankruptcy claim	0		0		21,992
Gain on sale of assets	1,782		0		0
Interest and other income, net	1,985		1,784		3,300
TOTAL REVENUES	978,599		921,342		701,802
EXPENSES
Operating costs - oil and gas production	272,180		237,296		189,809
Operating costs- electricity generation	19,975		25,690		31,295
Production taxes	39,374		33,617		22,999
Depreciation, depletion & amortization	227,700		215,822		182,657
Natural gas marketing	6,873		13,038		19,896
General and administrative	71,766		61,727		52,846
Interest	83,136		72,807		66,541
Extinguishment of debt	41,545		15,544		573
Realized and unrealized (gain) loss on derivatives, net	(64,620)		(13,908)		31,847
Gain on purchase	0		(1,046)		0
Transaction costs on acquisitions	0		0		2,635
Bad debt recovery	0		0		(38,508)
Impairment of oil and natural gas properties	79		625,564		0
Dry hole, abandonment, impairment and exploration	20,931		5,482		2,720
TOTAL EXPENSES	718,939		1,291,633		565,310
Earnings before income taxes	259,660		(370,291)		136,492
Income tax provision (benefit)	88,121		(142,228)		53,968
Net earnings (loss)	171,539		(228,063)		82,524
Basic net earnings (loss) per share	$ 3.11	[1],[2]	$ (4.21)	[1],[2]	$ 1.54
Diluted net earnings (loss) per share	$ 3.09	[1],[2]	$ (4.21)	[1],[2]	$ 1.52
Dividends per share	$ 0.32		$ 0.31		$ 0.30
Electricity Generation
EXPENSES
Depreciation, depletion & amortization	1,808		1,963		3,225
Oil and Natural Gas Properties, Buildings, and Equipment
EXPENSES
Depreciation, depletion & amortization	$ 225,892		$ 213,859		$ 179,432

[1] (4)The sum of the individual quarterly net earnings (loss) per common share amounts may not agree with year-to-date net earnings (loss) 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 earnings (loss) per common share for each quarter in which the Company reported net earnings.

[2] (3)Due to the volatility of commodity prices, the estimated fair value of the Company's commodity derivative instruments is subject to fluctuations. As a result, the Company may recognize significant unrealized gains and losses (non-cash changes in fair value) on commodity derivative instruments from period to period.