Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 781,531
Change in accumulated other comprehensive income (loss) before reclassifications	20,943	$ (9,361)
Reclassification adjustments from accumulated other comprehensive income (loss)	596	2,026
Ending balance	817,662	736,766
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(54,781)	(50,957)
Ending balance	(33,242)	$ (58,292)
Net unrealized gain (loss) on investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(72,241)
Change in accumulated other comprehensive income (loss) before reclassifications	19,943
Reclassification adjustments from accumulated other comprehensive income (loss)	596
Ending balance	(51,702)
Net benefit plan assets and obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	17,660
Change in accumulated other comprehensive income (loss) before reclassifications	(572)
Reclassification adjustments from accumulated other comprehensive income (loss)	0
Ending balance	17,088
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(200)
Change in accumulated other comprehensive income (loss) before reclassifications	1,572
Reclassification adjustments from accumulated other comprehensive income (loss)	0
Ending balance	$ 1,372