Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Center	Jun. 30, 2012	Dec. 31, 2012
Oil & Gas properties [Abstract]
Unproved	$ 8,736,000		$ 8,736,000		$ 9,169,000
Wells in progress	458,000		458,000		0
Proved	121,525,000		121,525,000		119,919,000
Oil & Gas properties	130,719,000		130,719,000		129,088,000
Less accumulated depreciation depletion and amortization	(50,128,000)		(50,128,000)		(43,454,000)
Net book value	80,591,000		80,591,000		85,634,000
Mineral properties	20,739,000		20,739,000		20,739,000
Building, land and equipment	8,410,000		8,410,000		8,469,000
Less accumulated depreciation	(4,117,000)		(4,117,000)		(4,034,000)
Net book value	4,293,000		4,293,000		4,435,000
Net properties and equipment	105,623,000		105,623,000		110,808,000
Oil and Gas Properties [Abstract]
Capitalized costs excluded from amortized cost pool	9,200,000		9,200,000		9,200,000
Capitalized costs related to unevaluated properties included in the amortization base	0		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)	91.60		92.63
Price for natural gas at ceiling test (dollars per MMbtu)	3.444		2.950
Proved property impairments	0	523,000	5,828,000	523,000
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		$ 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