Other Comprehensive Income (Loss) (AOCI Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plan adjustments/Unrealized loss in fair value of investment adjustments	$ (2,967)	$ (397)	$ (12,442)	$ (5,114)
Income tax benefit	(4,086)	560	(52,004)	(47,047)
Net of tax	36,896	32,455	123,626	117,092
Defined benefit pension plan adjustments | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plan adjustments/Unrealized loss in fair value of investment adjustments	413	639	1,239	1,916
Income tax benefit	(114)	(181)	(343)	(543)
Net of tax	299	458	896	1,373
Unrealized loss in fair value of investment adjustments | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plan adjustments/Unrealized loss in fair value of investment adjustments	18	79	103	121
Income tax benefit	(4)	(16)	(22)	(25)
Net of tax	$ 14	$ 63	$ 81	$ 96