v3.25.2
Derivative instruments - Schedule of Fair value of derivative instruments not designated as hedging (Details) - Natural gas swaps - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Assets    
Net Carrying Value Presented on the Balance Sheet $ 36,027 $ 28,624
Liabilities    
Assets 40,982 37,383
Liabilities (4,955) (8,759)
Net Carrying Value Presented on the Balance Sheet 36,027 28,624
Other current assets    
Assets    
Assets 22,797 19,527
Liabilities (1,060) (1,563)
Net Carrying Value Presented on the Balance Sheet 21,737 17,964
Other deferred charges    
Assets    
Assets 18,049 17,566
Liabilities (3,239) (5,279)
Net Carrying Value Presented on the Balance Sheet 14,810 12,287
Other current liabilities    
Liabilities    
Assets 136 290
Liabilities (656) (1,917)
Net Carrying Value Presented on the Balance Sheet $ (520) (1,627)
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Other current liabilities  
Other deferred credits    
Liabilities    
Assets $ 0 0
Liabilities 0 0
Net Carrying Value Presented on the Balance Sheet $ 0 $ 0