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, 2017	$ 1,301,147	$ (253,302)	$ 667	$ (346,245)	$ 609,471	$ 310	$ 1,312,048
Increase (Decrease) in Stockholders' Equity
Net Income	154,071					20	154,091
Adoption of accounting standards | Accounting Standards Update 2014-09	2,937						2,937
Foreign currency translation adjustments		(53,141)				(16)	(53,157)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		4,032					4,032
Changes in treasury locks, net of tax		17					17
Changes in derivative gains (losses), net of tax		1,046					1,046
Stock awards and option exercises			11	26,009	67,705		93,725
Cash dividends declared on common stock	(60,989)						(60,989)
Treasury stock purchased				(3,905)			(3,905)
Common stock repurchased and retired	(51,315)		(6)		(6,466)		(57,787)
Balance at Sep. 30, 2018	1,345,851	(301,348)	672	(324,141)	670,710	314	1,392,058
Balance at Jun. 30, 2018	1,328,034	(291,660)	668	(336,278)	646,449	299	1,347,512
Increase (Decrease) in Stockholders' Equity
Net Income	38,996					26	39,022
Foreign currency translation adjustments		(9,858)				(11)	(9,869)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		1,333					1,333
Changes in treasury locks, net of tax		3					3
Changes in derivative gains (losses), net of tax		(1,166)					(1,166)
Stock awards and option exercises			4	12,137	24,261		36,402
Cash dividends declared on common stock	(21,179)						(21,179)
Balance at Sep. 30, 2018	1,345,851	(301,348)	672	(324,141)	670,710	314	1,392,058
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	193,669					20	193,689
Foreign currency translation adjustments		(42,725)				(12)	(42,737)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		2,150					2,150
Changes in derivative gains (losses), net of tax		(593)					(593)
Stock awards and option exercises			12	22,436	78,219		100,667
Cash dividends declared on common stock	(67,195)						(67,195)
Treasury stock purchased				(54,873)			(54,873)
Balance at Sep. 30, 2019	1,498,300	(351,672)	685	(350,645)	756,988	323	1,553,979
Balance at Jun. 30, 2019	1,464,607	(310,136)	683	(317,380)	743,332	316	1,581,422
Increase (Decrease) in Stockholders' Equity
Net Income	56,750					19	56,769
Foreign currency translation adjustments		(42,528)				(12)	(42,540)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		713					713
Changes in derivative gains (losses), net of tax		279					279
Stock awards and option exercises			2	2,512	13,656		16,170
Cash dividends declared on common stock	(23,057)						(23,057)
Treasury stock purchased				(35,777)			(35,777)
Balance at Sep. 30, 2019	$ 1,498,300	$ (351,672)	$ 685	$ (350,645)	$ 756,988	$ 323	$ 1,553,979