v3.26.1
Goodwill - Changes in carrying amount and impairment testing (Details)
 12 Months Ended
Dec. 31, 2025
USD ($)
item
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period $ 14,219,000    
Impairment (1,747,000) $ (15,483,000)  
Goodwill at end of period $ 12,472,000 14,219,000  
Number of Cash Generating Units | item 2    
Acquisition cost      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period $ 29,702,000 29,702,000  
Goodwill at end of period 29,702,000 29,702,000 $ 29,702,000
Impairment      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period (15,483,000)    
Impairment (1,747,000) (15,483,000)  
Goodwill at end of period (17,230,000) (15,483,000)  
U.S. Silicon Metal      
Reconciliation of changes in goodwill [abstract]      
Impairment (1,747,000) (15,483,000) 0
U.S. Silicon Metal | Acquisition cost      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period 17,230,000 17,230,000  
Goodwill at end of period 17,230,000 17,230,000 17,230,000
U.S. Silicon Metal | Impairment      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period (15,483,000)    
Impairment (1,747,000) (15,483,000)  
Goodwill at end of period (17,230,000) (15,483,000)  
U.S. Silicon Based Alloys      
Reconciliation of changes in goodwill [abstract]      
Goodwill at end of period 12,472,000    
U.S. Silicon Based Alloys | Acquisition cost      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period 12,472,000 12,472,000  
Additions 0 0  
Goodwill at end of period 12,472,000 12,472,000 12,472,000
U.S. Silicon Based Alloys | Impairment      
Reconciliation of changes in goodwill [abstract]      
Goodwill at beginning of period 0 0  
Impairment 0 0  
Goodwill at end of period $ 0 $ 0 $ 0