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Fair Value Measurements and Derivative Instruments - Schedule of Outstanding Fuel Swap Agreements (Details) - Fuel Swap Agreements - T
Jun. 30, 2025
Dec. 31, 2024
2025    
Derivative Instruments    
Fuel swap agreements (metric tons) 513,050 1,031,449
Percentage of projected requirements 59.00% 60.00%
2026    
Derivative Instruments    
Fuel swap agreements (metric tons) 1,050,150 786,750
Percentage of projected requirements 59.00% 44.00%
2027    
Derivative Instruments    
Fuel swap agreements (metric tons) 819,048 364,048
Percentage of projected requirements 47.00% 20.00%
2028    
Derivative Instruments    
Fuel swap agreements (metric tons) 284,099 0
Percentage of projected requirements 16.00% 0.00%