Inventories (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Inventories
Raw materials	$ 28,501,000	$ 32,910,000
Work in process	54,281,000	50,008,000
Finished goods	3,161,000	3,585,000
Inventories, Total	85,943,000	86,503,000
Inventory reserve	22,200,000	21,900,000
Excess and obsolete inventory	$ 213,000	$ 78,000