Pension and Other Postretirement Benefit Plans - Schedule of Changes in Benefit Obligation, Plan Assets and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Change in plan assets:
Fair value of plan assets at beginning of period	$ 511,472
Fair value of plan assets at end of period	515,407	$ 511,472
Funded status:
Noncurrent assets	49,618	41,938
Pension Benefits
Change in benefit obligation:
Benefit obligation at beginning of period	491,664	525,086
Service cost	1,100	1,208	$ 1,217
Interest cost	25,373	25,724	27,027
Benefit obligations assumed in Merger	894	0
Plan curtailments	0	(217)
Actuarial loss (gain)	11,094	(14,615)
Benefits and other payments	(41,073)	(45,522)
Benefit obligation at end of period	489,052	491,664	525,086
Change in plan assets:
Fair value of plan assets at beginning of period	511,472	549,571
Actual return on plan assets	43,278	5,695
Company contributions	1,730	1,728
Benefits and other payments	(41,073)	(45,522)
Fair value of plan assets at end of period	515,407	511,472	549,571
Funded status:
Noncurrent assets	49,618	41,938
Current liabilities	(2,152)	(2,057)
Noncurrent liabilities	(21,111)	(20,073)
Net asset (obligation) recognized	26,355	19,808
Amounts recognized in accumulated other comprehensive (loss) income consist of:
Net actuarial loss (gain)	243,082	253,641
Prior service credit	0	0
Net amount recognized (before tax effect)	243,082	253,641
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at beginning of period	194,138	227,235
Service cost	146	0	0
Interest cost	11,876	11,031	13,044
Benefit obligations assumed in Merger	41,365	0
Plan curtailments	0	0
Actuarial loss (gain)	(23,753)	(27,445)
Benefits and other payments	(18,233)	(16,683)
Benefit obligation at end of period	205,539	194,138	227,235
Change in plan assets:
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0	0
Company contributions	18,233	16,683
Benefits and other payments	(18,233)	(16,683)
Fair value of plan assets at end of period	0	0	$ 0
Funded status:
Noncurrent assets	0	0
Current liabilities	(18,696)	(17,887)
Noncurrent liabilities	(186,843)	(176,251)
Net asset (obligation) recognized	(205,539)	(194,138)
Amounts recognized in accumulated other comprehensive (loss) income consist of:
Net actuarial loss (gain)	(74,435)	(53,416)
Prior service credit	(6,519)	(8,924)
Net amount recognized (before tax effect)	$ (80,954)	$ (62,340)