v3.26.3
Accumulated Other Comprehensive Loss - Schedule of Components of Accumulated Other Comprehensive Loss, Net of Related Deferred Income Taxes (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax $ (1,068,164) $ (1,055,155) $ (1,025,680) $ (1,036,494) $ (950,808) $ (1,804,310) $ (1,559,018) $ (1,604,699)
Total accumulated other comprehensive loss, net of tax                
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax (64,996) $ (66,211) $ (67,260) (66,656) $ (74,477) $ (69,803) $ (75,318) $ (73,747)
Defined benefit pension and other postretirement benefit plans                
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax (68,418)     (70,603)        
Unrealized foreign currency translation gain                
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax 7,001     8,757        
Unrealized loss on interest rate swaps                
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax 0     (1,721)        
Share of other comprehensive loss of equity method investments                
Accumulated Other Comprehensive Income (Loss) [Line Items]                
Total accumulated other comprehensive loss, net of tax $ (3,579)     $ (3,089)