v3.25.4
Contract Obligations (Narrative) (Details)
T in Thousands, $ in Thousands, $ in Millions
 12 Months Ended
Dec. 31, 2025
AUD ($)
Item
T
Dec. 31, 2025
USD ($)
Item
T
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2025
USD ($)
Other Commitments [Line Items]          
Contract obligation     $ 349,912   $ 545,413
Non-Market Coal Supply Agreement [Member]          
Other Commitments [Line Items]          
Non-market portion of the coal leases         27,300
Amortization of liability   $ 23,400 $ 31,100 $ 32,800  
Amortization for the liability $ 400.0 307,000      
Stanwell Reserved Area Deferred Consideration [Member]          
Other Commitments [Line Items]          
Deferred consideration liability, long-term $ 210.0       $ 155,200
Pre-tax discount 13.00%       13.00%
Stanwell Prepaid Coal Supply Liability [Member]          
Other Commitments [Line Items]          
Amount of near term liquidity provided from agreement   150,000      
Prepayment future coal sales $ 116.1       $ 75,000
Estimated value of rebate $ 103.1 $ 67,200      
Prepayment, discount period 5 years 5 years      
Prepaid coal supply liability interest rate 13.00% 13.00%      
Interest expense $ 12.4 $ 8,100      
Maximum annual nominations | T 800 800      
Second Amendment Deed [Member]          
Other Commitments [Line Items]          
Liquidity benchmark for prepayment settlement   $ 300,000      
Prepayment and deferred payment balance, interest rate 7.50% 7.50%      
Accrued interest amount capped, times | Item 1.2 1.2      
Cash liquidity benchmark for distributions         $ 300,000
Second Amendment Deed [Member] | Maximum [Member]          
Other Commitments [Line Items]          
Liquidity benchmark for prepayments   $ 250,000      
Range of broader annual nominations | T 2,240 2,240      
Second Amendment Deed [Member] | Minimum [Member]          
Other Commitments [Line Items]          
Liquidity benchmark for prepayments   $ 200,000      
Range of broader annual nominations | T 1,200 1,200