OIL AND GAS INFORMATION (Details) (USD $)	12 Months Ended			60 Months Ended	96 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012
OIL AND GAS INFORMATION
Property acquisition-proved	$ 5,413,000	$ 509,000	$ 1,685,000
Exploration costs	52,000	8,147,000	204,000
Development costs	65,676,000	63,675,000	26,220,000
Total Costs related to oil and gas activities	71,141,000	72,331,000	28,109,000
Increase in asset retirement cost	9,500,000	5,300,000	1,400,000
Aggregate capitalized costs
Unproved oil and gas properties	20,507,000	22,963,000			20,507,000
Proved oil and gas properties	730,353,000	657,445,000			730,353,000
Gross capitalized costs	750,860,000	680,408,000			750,860,000
Less accumulated depreciation, depletion, amortization and impairment expense	449,261,000	404,965,000			449,261,000
Total aggregate capitalized costs relating to oil and gas activities	301,599,000	275,443,000			301,599,000
Results of operations from oil and natural gas producing activities
Revenues	121,797,000	103,371,000	88,275,000
Production costs	(33,072,000)	(30,637,000)	(28,845,000)
Accretion of asset retirement obligation	(1,525,000)	(995,000)	(820,000)
Depreciation, depletion, amortization	(43,460,000)	(27,914,000)	(20,265,000)
Income from oil and gas producing activities	43,740,000	43,825,000	38,345,000
Oil and gas properties not subject to amortization
Acquisition costs				834,000	834,000
Exploration costs		60,000			60,000
Development costs	311,000	161,000	266,000	18,875,000	19,613,000
Total oil and gas properties not subject to amortization	$ 311,000	$ 221,000	$ 266,000	$ 19,709,000	$ 20,507,000
Minimum
Development costs
Expected drilling period of wells	5 years
Maximum
Development costs
Expected drilling period of wells	8 years