v3.25.4
Employee Benefit Plans and Other Postretirement Benefits - Schedule of Obligation and Funded Status (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Change in plan assets:      
Pension and postretirement assets $ 546,303 $ 440,825  
Pension and SERPA Benefits      
Change in benefit obligation:      
Benefit obligation, beginning of period 1,506,747 1,568,277  
Service cost 3,854 4,698 $ 5,174
Interest cost 82,006 80,478 81,911
Actuarial loss / (gains) 15,059 (41,748)  
Plan participant contributions 0 0  
Special early retirement benefits 0 1,722  
Plan amendments 0 5,601  
Benefits paid (113,359) (112,281)  
Settlements (531) 0  
Benefit obligation, end of period 1,493,776 1,506,747 1,568,277
Change in plan assets:      
Fair value of plan assets, beginning of period 1,839,779 1,901,824  
Return on plan assets 154,449 49,572  
Plan participant contributions 0 0  
Benefits paid (112,780) (111,617)  
Fair value of plan assets, end of period 1,881,448 1,839,779 1,901,824
Funded status of the plan 387,672 333,032  
Pension and postretirement assets 397,107 342,569  
Accrued liabilities (1,245) (1,176)  
Pension and postretirement liabilities (8,190) (8,361)  
Total benefits included in balance sheet 387,672 333,032  
Prior service credits 5,452 6,597  
Actuarial losses (gains) 304,523 310,065  
Amounts included in other comprehensive income, net of tax 309,975 316,662  
Postretirement Healthcare Benefits      
Change in benefit obligation:      
Benefit obligation, beginning of period 191,747 206,506  
Service cost 2,571 2,892 3,184
Interest cost 10,470 10,775 11,089
Actuarial loss / (gains) (17,916) (15,269)  
Plan participant contributions 488 564  
Special early retirement benefits 0 0  
Plan amendments 0 0  
Benefits paid (15,106) (13,721)  
Settlements 0 0  
Benefit obligation, end of period 172,254 191,747 206,506
Change in plan assets:      
Fair value of plan assets, beginning of period 244,490 225,167  
Return on plan assets 40,909 28,067  
Plan participant contributions 488 564  
Benefits paid (9,382) (9,308)  
Fair value of plan assets, end of period 276,505 244,490 $ 225,167
Funded status of the plan 104,251 52,743  
Pension and postretirement assets 149,196 98,256  
Accrued liabilities 0 0  
Pension and postretirement liabilities (44,945) (45,513)  
Total benefits included in balance sheet 104,251 52,743  
Prior service credits 7,638 8,087  
Actuarial losses (gains) (101,711) (75,603)  
Amounts included in other comprehensive income, net of tax $ (94,073) $ (67,516)