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Summary of Significant Accounting Policies (Details) (USD $)
 3 Months Ended 12 Months Ended
Mar. 31, 2013
Costcenter
Mar. 31, 2012
Dec. 31, 2012
Oil & Gas properties [Abstract]      
Unproved $ 9,171,000   $ 9,169,000
Proved 119,945,000   119,919,000
Oil & Gas properties 129,116,000   129,088,000
Less accumulated depreciation depletion and amortization (46,915,000)   (43,454,000)
Net book value 82,201,000   85,634,000
Mineral properties 20,739,000   20,739,000
Building, land and equipment 8,410,000   8,469,000
Less accumulated depreciation (4,048,000)   (4,034,000)
Net book value 4,362,000   4,435,000
Net properties and equipment 107,302,000   110,808,000
Oil and Gas Properties [Abstract]      
Capitalized costs excluded from amortized cost pool 9,200,000   9,200,000
Capitalized costs related to unevaluated properties included in the amortization base 0   0
Period after which costs will be added to the full cost amortization pool for properties 2 years    
Percentage of discount used for future net revenue (in hundredths) 10.00%    
Period for calculating unescalated average prices prior to the end of reporting period 12 months    
Number of cost centers for quarterly ceiling test for oil and gas 1    
Price per barrel for oil at ceiling test (in dollars per barrel) 92.63    
Price for natural gas at ceiling test (dollars per MMbtu) 2.950    
Proved property impairments 5,828,000 0  
Mineral Properties [Abstract]      
Costs associated with Mount Emmons beginning of year 20,739,000 20,739,000 20,739,000
Development costs 0   0
Costs at the end of the period $ 20,739,000   $ 20,739,000
Minimum [Member]
      
Property, Plant and Equipment [Line Items]      
Estimated useful lives 3 years    
Maximum [Member]
      
Property, Plant and Equipment [Line Items]      
Estimated useful lives 45 years