Accumulated Other Comprehensive Earnings (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	$ 750,622
Adoption of ASU 2018-02 (See Note 1)		$ 2,726
Balance at the end of the period	744,828	726,520
Foreign Currency Derivatives | Foreign currency forward contracts
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(309)	51
Other comprehensive earnings (loss) before reclassifications	159	(8)
Reclassifications from accumulated other comprehensive loss		(36)
Other comprehensive earnings (loss) net of tax	159	(44)
Adoption of ASU 2018-02 (See Note 1)		9
Balance at the end of the period	(150)	16
Foreign Currency Derivatives | Commodity futures contracts
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(444)	20
Other comprehensive earnings (loss) before reclassifications	258	(1,107)
Reclassifications from accumulated other comprehensive loss	72	253
Other comprehensive earnings (loss) net of tax	330	(854)
Adoption of ASU 2018-02 (See Note 1)		4
Balance at the end of the period	(114)	(830)
Investments
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(1,516)	(889)
Other comprehensive earnings (loss) before reclassifications	1,112	(948)
Other comprehensive earnings (loss) net of tax	1,112	(948)
Adoption of ASU 2018-02 (See Note 1)		(168)
Balance at the end of the period	(404)	(2,005)
Postretirement and Pension Benefits
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	4,206	3,289
Reclassifications from accumulated other comprehensive loss	(288)	(251)
Other comprehensive earnings (loss) net of tax	(288)	(251)
Adoption of ASU 2018-02 (See Note 1)		748
Balance at the end of the period	3,918	3,786
Foreign Currency Translation
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(24,159)	(24,262)
Other comprehensive earnings (loss) before reclassifications	391	1,612
Other comprehensive earnings (loss) net of tax	391	1,612
Balance at the end of the period	(23,768)	(22,650)
Accumulated Other Comprehensive Earnings ( Loss )
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(22,222)	(21,791)
Other comprehensive earnings (loss) before reclassifications	1,920	(451)
Reclassifications from accumulated other comprehensive loss	(216)	(34)
Other comprehensive earnings (loss) net of tax	1,704	(485)
Adoption of ASU 2018-02 (See Note 1)		593
Balance at the end of the period	$ (20,518)	$ (21,683)