CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Common Stock Par Value	Treasury Stock	Capital in Excess of Par Value	Non-Controlling Interest	Total
Balance at Dec. 31, 2018	$ 1,371,826	$ (310,504)	$ 673	$ (318,208)	$ 678,769	$ 315	$ 1,422,871
Increase (Decrease) in Stockholders' Equity
Net Income	63,004					(5)	62,999
Foreign currency translation adjustments		(9,619)				8	(9,611)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		721					721
Changes in derivative gains (losses), net of tax		(393)					(393)
Stock awards and option exercises			3	5,337	22,164		27,504
Cash dividends declared on common stock	(21,377)						(21,377)
Treasury stock purchased				(15,000)			(15,000)
Balance at Mar. 31, 2019	1,413,453	(319,795)	676	(327,871)	700,933	318	1,467,714
Balance at Dec. 31, 2019	1,523,820	(341,948)	686	(381,238)	770,596	336	1,572,252
Increase (Decrease) in Stockholders' Equity
Net Income	55,253					(3)	55,250
Adoption of accounting standards | Accounting Standards Update 2016-13	(1,377)						(1,377)
Foreign currency translation adjustments		(42,229)					(42,229)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		1,636					1,636
Changes in derivative gains (losses), net of tax		1,483					1,483
Stock awards and option exercises			3	8,665	14,971		23,639
Cash dividends declared on common stock	(23,031)						(23,031)
Balance at Mar. 31, 2020	$ 1,554,665	$ (381,058)	$ 689	$ (372,573)	$ 785,567	$ 333	$ 1,587,623