Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended			0 Months Ended	3 Months Ended	12 Months Ended																	12 Months Ended
	Dec. 31, 2011 Purchasers Cogeneration_facilities Industry_Segments	Dec. 31, 2010 Purchasers	Dec. 31, 2009 Purchasers	Jul. 23, 2010 Flying J	Sep. 30, 2010 Flying J	Dec. 31, 2008 Flying J	Dec. 31, 2011 Building and Building Improvements year	Dec. 31, 2011 Machinery and Equipment year	Dec. 31, 2011 California Shell Trading (US) and Exxon Mobil Oil Corporation	Dec. 31, 2011 Electricity Cost Allocation	Dec. 31, 2010 Electricity Cost Allocation	Dec. 31, 2009 Electricity Cost Allocation	Dec. 31, 2011 Costs of Transporting Natural Gas	Dec. 31, 2010 Costs of Transporting Natural Gas	Dec. 31, 2009 Costs of Transporting Natural Gas	Dec. 31, 2011 Sales Shell Trading (US) Company	Dec. 31, 2011 Sales ExxonMobil Oil Corporation	Dec. 31, 2010 Sales Purchaser One	Dec. 31, 2009 Sales Purchaser One	Dec. 31, 2010 Sales Purchaser Two	Dec. 31, 2009 Sales Purchaser Two	Dec. 31, 2009 Sales Purchaser Three	Dec. 31, 2011 East Texas Oil and Gas Properties Assets measured on nonrecurring basis
Accounting Policies
Electricity Consumption Included in Operating Costs-Oil and Natural Gas Production										$ 2,300,000	$ 2,800,000	$ 2,800,000
Outstanding checks in excess of the bank balance, included in accounts payable	16,100,000	16,300,000
Oil and natural gas receivables generally collected (in months)	2 months
Bad debt expense						38,500,000
Litigation settlement, gross				60,500,000
Proceeds received from bankruptcy claim				60,500,000
Settlement of Flying J bankruptcy claim	0	21,992,000	0		22,000,000
Allowance for doubtful accounts recoveries of bad debts	0	38,508,000	0		38,500,000
Property, plant and equipment, useful lives, minimum (in years)							5	3
Property, plant and equipment, useful lives, maximum (in years)							30	10
Significant customer, amount (in ones)	2	2	3
Concentration risk (as a percent)																14.00%	43.00%	44.00%	25.00%	14.00%	16.00%	12.00%
Oil production under contract (as a percent)									87.00%
Contract renewal automatic on month-to-month basis unless either party to contract gives termination notice (number of days in advance)	90 days
Natural Gas Transportation Costs Included in Operating Costs-Oil and Natural Gas Production													21,400,000	16,200,000	16,100,000
Costs of Natural Gas Transportation Used in Electricity Generation													5,000,000	4,700,000	2,800,000
Number of companies owned under equity method investments (in ones)	2
Equity method investment, ownership is less than (as a percent)	50.00%
Exploratory wells are evaluated for economic viability after well completion, length of time (in years)	1 year
Impairment of oil and natural gas properties	$ 625,564,000	$ 0	$ 1,017,000																				$ 625,000,000
Number of Cogeneration facilities (in ones)	3
Number of industry segments (in ones)	1