v3.26.1
Workers' Compensation and Pneumoconiosis - Benefit cost (Details) - Pneumoconiosis benefits - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 723 $ 889 $ 1,443 $ 1,748
Interest cost $ 1,399 $ 1,686 $ 2,797 $ 3,352
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Other Nonoperating Income (Expense) Other Nonoperating Income (Expense) Other Nonoperating Income (Expense) Other Nonoperating Income (Expense)
Amortization of net actuarial loss $ 116 $ 232 $ 232 $ 464
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax
Other adjustments $ 0 $ 0 $ (6,450) $ 0
Net periodic benefit credit $ 2,238 $ 2,807 $ (1,978) $ 5,564