Oil and Gas Exploration and Production Industries Disclosures (Details 6) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Extensions	$ 0	$ 0	$ 0
Revisions of previous estimates
Price changes	(2,155,000)	7,026,000	4,962,000
Quantity estimates	(894,000)	1,901,000	2,016,000
Change in production rates, timing and other	(1,642,000)	(1,157,000)	(2,136,000)
Development costs incurred	858,000	1,023,000	941,000
Changes in estimated future development costs	(1,281,000)	315,000	(46,000)
Estimated future abandonment costs	(6,000)	8,000	(4,000)
Sales of oil and gas, net of production costs	(2,892,000)	(3,768,000)	(2,817,000)
Accretion of discount	1,922,000	1,386,000	994,000
Standardized Measure Of Discounted Future Net Cash Flow Of Proved Oil and Gas Reserves	(6,090,000)	6,734,000	3,910,000
Net change in income taxes	(1,703,000)	1,778,000	1,106,000
Net (decrease) increase	$ (4,387,000)	$ 4,956,000	$ 2,804,000