v3.26.1
Merger with Arch - Narrative (Details)
$ in Thousands, shares in Millions
3 Months Ended 6 Months Ended
Jan. 14, 2025
USD ($)
terminal
mine
state
shares
Jan. 13, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Business Combination [Line Items]            
Number of states operating with mining and terminal facilities | state 6          
Number of export terminals with ownership interest | terminal 2          
Amortization expenses     $ 2,000 $ 11,000 $ 4,000 $ 15,000
Expected amortization rate in 2026     8.00%   8.00%  
Expected amortization rate in 2027     16.00%   16.00%  
Expected amortization rate in 2028     2.00%   2.00%  
Expected amortization rate in 2029     2.00%   2.00%  
Arch Resources, Inc            
Business Combination [Line Items]            
Stock issued (in shares) | shares 24.3          
Business acquisition, percentage 45.00%          
Equity portion of purchase consideration $ 2,481,368          
Purchase price consideration   $ 98,075        
Number of mines | mine 11          
Gross contractual amount of receivables $ 168,299          
Property, plant and equipment 1,400,000          
Liability for below market lease acquired $ 37,000          
Amortized over a weighted average remaining contract term 1 year 7 months 6 days          
Arch Resources, Inc | Nonrecurring Adjustments            
Business Combination [Line Items]            
Pro forma expense adjustments (before tax)           37,692
Arch Resources, Inc | Nonrecurring Adjustment, Merger-Related Costs            
Business Combination [Line Items]            
Pro forma expense adjustments (before tax)           35,133
Arch Resources, Inc | Nonrecurring Adjustment, Inventory Fair Value Adjustment            
Business Combination [Line Items]            
Pro forma expense adjustments (before tax)           $ 2,559
Arch Resources, Inc | Above Market Leases            
Business Combination [Line Items]            
Intangible assets acquired $ 84,000          
Arch Resources, Inc | Minimum            
Business Combination [Line Items]            
Identified intangible assets amortized, contract term 1 year          
Arch Resources, Inc | Maximum            
Business Combination [Line Items]            
Identified intangible assets amortized, contract term 5 years