Inventories (Details) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Inventories
Raw materials	$ 28,939,000	$ 32,910,000
Work in process	53,854,000	50,008,000
Finished goods	2,981,000	3,585,000
Inventories, Total	85,774,000	86,503,000
Inventory reserve	23,100,000	21,900,000
Excess and obsolete inventory	$ 161,000	$ 78,000