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, 2015	$ 1,185,681	$ (262,347)	$ 667	$ (270,052)	$ 495,462	$ 295	$ 1,149,706
Increase (Decrease) in Stockholders' Equity
Net Income	205,590					14	205,604
Foreign currency translation adjustments		(53,163)				(20)	(53,183)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		(4,225)					(4,225)
Changes in treasury locks, net of tax		26					26
Stock awards and option exercises			10	19,135	65,198		84,343
Cash dividends declared on common stock	(76,659)						(76,659)
Common stock repurchased and retired	(117,378)		(17)		(13,976)		(131,371)
Non controlling interest addition					(2)	3	1
Balance at Dec. 31, 2016	1,197,234	(319,709)	660	(250,917)	546,682	292	1,174,242
Increase (Decrease) in Stockholders' Equity
Net Income	220,030					(1)	220,029
Foreign currency translation adjustments		74,385				19	74,404
Changes in unrecognized pension gains (losses) and related amortization, net of tax		(4,820)					(4,820)
Changes in treasury locks, net of tax		28					28
Changes in derivative gains (losses), net of tax		(3,186)					(3,186)
Stock awards and option exercises			12	25,212	67,605		92,829
Cash dividends declared on common stock	(79,944)						(79,944)
Treasury stock purchased				(120,540)			(120,540)
Common stock repurchased and retired	(36,173)		(5)		(4,816)		(40,994)
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	194,745					21	194,766
Adoption of accounting standards | Accounting Standards Update 2014-09	2,937						2,937
Adoption of accounting standards | Accounting Standards Update 2018-02	6,658	(6,658)
Foreign currency translation adjustments		(62,898)				(16)	(62,914)
Changes in unrecognized pension gains (losses) and related amortization, net of tax		10,790					10,790
Changes in treasury locks, net of tax		17					17
Changes in derivative gains (losses), net of tax		1,547					1,547
Stock awards and option exercises			12	31,942	75,763		107,717
Cash dividends declared on common stock	(82,346)						(82,346)
Treasury stock purchased				(3,905)			(3,905)
Common stock repurchased and retired	(51,315)		(6)		(6,465)		(57,786)
Balance at Dec. 31, 2018	$ 1,371,826	$ (310,504)	$ 673	$ (318,208)	$ 678,769	$ 315	$ 1,422,871