Postretirement Benefits - Reconciliation of Benefit Obligation and Plan Assets, Pension Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Changes in PBO:
PBO at beginning of year	$ 635,056
Service cost	24,969	$ 24,898	$ 21,568
Interest cost	36,081	33,123	31,367
PBO at end of year	676,788	635,056
Pension and SERP Plans
Changes in PBO:
PBO at beginning of year	635,056	627,560
Service cost	24,969	24,898
Interest cost	36,081	33,123
Plan amendments	0	1,212
Actuarial loss (gain)	10,252	(22,964)
Benefits paid	(29,570)	(28,773)
PBO at end of year	676,788	635,056	627,560
Changes in plan assets:
Fair value at beginning of year	614,845	570,767
Return on assets	67,459	48,084
Contributions	26,488	24,767
Benefits paid	(29,570)	(28,773)
Fair value at end of year	679,222	614,845	$ 570,767
Funded status at year end	$ 2,434	$ (20,211)