Summary of Significant Accounting Policies - PP&E, ARO and Other (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment
Construction in progress	$ 6,001,000	$ 6,534,000
Interest costs capitalized	0	0
Capitalized cost in accounts payable and accrued expenses	1,196,000	1,079,000
Impairment of long-lived assets	0	0
Asset Retirement Obligations
ARO included in other liabilities and accrued expenses	1,548,000	1,556,000
Amount of assets associated with AROs not fully depreciated	603,000
Amount spent on AROs	36,000	24,000
Accretion expense recognized on AROs	99,000	97,000	$ 92,000
Estimated annual expenditures in years 2023 through 2027 relating to AROs	100,000
Accrued Expenses
Personnel related expenses	4,073,000	2,970,000
Income taxes	2,010,000	237,000
Other taxes	1,112,000	1,208,000
Utilities	944,000	1,207,000
Other	366,000	779,000
Total accrued expenses	8,505,000	6,401,000
Environmental Expenditures
Capital expenditures related to environmental matters	1,456,000	779,000	665,000
Selling, general and administrative expense.
Property, Plant and Equipment
Depreciation	$ 294,000	$ 278,000	$ 268,000
Buildings and building improvements and leasehold improvements | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Buildings and building improvements and leasehold improvements | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	25 years
Machinery and equipment | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	2 years
Machinery and equipment | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	30 years
Furniture and fixtures | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	10 years
Automotive equipment. | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Automotive equipment. | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	10 years