Additional Operations and Balance Sheet Information - Revenues, costs and expenses related to the Company's oil and gas operations (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) $ / Mcfe	Dec. 31, 2022 USD ($) $ / Mcfe	Dec. 31, 2021 USD ($) $ / Mcfe
Capitalized costs relating to oil and gas producing activities:
Unproved properties	$ 1,876,000	$ 1,876,000	$ 1,876,000
Proved properties	23,973,000	23,445,000	24,429,000
Total capitalized costs	25,849,000	25,321,000	26,305,000
Accumulated amortization	(25,438,000)	(25,304,000)	(25,304,000)
Total capitalized costs, net	411,000	17,000	1,001,000
Costs incurred in oil and gas property acquisitions, exploration and development:
Acquisition of properties			19,000
Development costs	565,000	214,000	410,000
Total costs incurred	565,000	214,000	429,000
Results of operations from producing activities:
Sales of oil and gas	$ 4,502,000	$ 7,775,000	$ 5,466,000
Amortization Expense Per Physical Unit of Production | $ / Mcfe	0.20		0.06
Oil and Gas Properties [Member]
Results of operations from producing activities:
Sales of oil and gas	$ 4,502,000	$ 7,775,000	$ 5,466,000
Production costs	2,170,000	2,987,000	2,103,000
Amortization of oil and gas properties	134,000		63,000
Total production costs	2,304,000	2,987,000	2,166,000
Total net revenue	$ 2,198,000	$ 4,788,000	$ 3,300,000
Sales price per equivalent Mcf | $ / Mcfe	5.56	8.97	5.58
Production costs per equivalent Mcf | $ / Mcfe	2.69	3.45	2.15
Results of operations from gas gathering and equipment rental activities:
Revenue	$ 120,000	$ 89,000	$ 99,000
Operating expenses	54,000	21,000	17,000
Depreciation	4,000	1,000	1,000
Total costs	58,000	22,000	18,000
Total net revenue	$ 62,000	$ 67,000	$ 81,000