Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (590,429)		$ (748,742)	$ (697,029)		$ (646,568)	$ (748,742)	$ (646,568)
Other comprehensive income (loss) before reclassifications (3)	(15,767)			49,792			138,781	(5,918)
Amounts reclassified from AOCL	1,863			882			5,628	6,131
Other comprehensive income (loss):	(13,904)			50,674			144,409	213
Ending balance	(604,333)	$ (590,429)		(646,355)	$ (697,029)		(604,333)	(646,355)
Foreign currency translation adjustment		(7,200)	(7,300)		(7,300)	(7,000)	(7,300)	(7,300)
Foreign currency translation items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(472,867)		(632,097)	(576,548)		(523,873)	(632,097)	(523,873)
Other comprehensive income (loss) before reclassifications (3)	(16,916)			52,872			142,314	(3,369)
Amounts reclassified from AOCL	0			0			0	3,566
Other comprehensive income (loss):	(16,916)			52,872			142,314	197
Ending balance	(489,783)	(472,867)		(523,676)	(576,548)		(489,783)	(523,676)
Pension and other postretirement effects
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(116,863)		(115,898)	(119,687)		(121,882)	(115,898)	(121,882)
Other comprehensive income (loss) before reclassifications (3)	1,149			(3,080)			(3,533)	(2,549)
Amounts reclassified from AOCL	1,838			859			5,555	2,523
Other comprehensive income (loss):	2,987			(2,221)			2,022	(26)
Ending balance	(113,876)	(116,863)		(121,908)	(119,687)		(113,876)	(121,908)
Cash flow hedging activity
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(699)		$ (747)	(794)		$ (813)	(747)	(813)
Other comprehensive income (loss) before reclassifications (3)	0			0			0	0
Amounts reclassified from AOCL	25			23			73	42
Other comprehensive income (loss):	25			23			73	42
Ending balance	(674)	$ (699)		(771)	$ (794)		(674)	(771)
Non- controlling Interests
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income (loss):	$ (118)			$ (1)			$ (25)	$ (286)