Accumulated Other Comprehensive Earnings (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	$ 763,327
Balance at the end of the period	758,816	$ 751,732
Foreign Currency Translation
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(24,581)	(23,368)
Other comprehensive earnings (loss) before reclassifications	(397)	(3,674)
Other comprehensive earnings (loss) net of tax	(397)	(3,674)
Balance at the end of the period	(24,978)	(27,042)
Investments
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	1,992	882
Other comprehensive earnings (loss) before reclassifications	(876)	(827)
Other comprehensive earnings (loss) net of tax	(876)	(827)
Balance at the end of the period	1,116	55
Foreign Currency Derivatives
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	589	10
Other comprehensive earnings (loss) before reclassifications	61	(155)
Reclassifications from accumulated other comprehensive loss	(78)	74
Other comprehensive earnings (loss) net of tax	(17)	(81)
Balance at the end of the period	572	(71)
Commodity Derivatives
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	713	92
Other comprehensive earnings (loss) before reclassifications	301	(574)
Reclassifications from accumulated other comprehensive loss	(506)	118
Other comprehensive earnings (loss) net of tax	(205)	(456)
Balance at the end of the period	508	(364)
Postretirement and Pension Benefits
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	1,472	2,139
Reclassifications from accumulated other comprehensive loss	(267)	(256)
Other comprehensive earnings (loss) net of tax	(267)	(256)
Balance at the end of the period	1,205	1,883
Accumulated Other Comprehensive Earnings ( Loss )
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(19,815)	(20,245)
Other comprehensive earnings (loss) before reclassifications	(911)	(5,230)
Reclassifications from accumulated other comprehensive loss	(851)	(64)
Other comprehensive earnings (loss) net of tax	(1,762)	(5,294)
Balance at the end of the period	$ (21,577)	$ (25,539)