CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Shares	Noncontrolling Interests
Beginning Balance at Dec. 31, 2015	$ 932,448	$ 9,858	$ 272,908	$ 2,125,838	$ (296,267)	$ (1,180,750)	$ 861
Beginning Balance (in shares) at Dec. 31, 2015		70,693,000
Increase (Decrease) in Stockholders' Equity
Net income	198,373			198,399			(26)
Unrecognized amounts from defined benefit pension plans, net of tax	3,837				3,837
Unrealized gain on derivatives designated and qualifying as cash flow hedges, net of tax	39				39
Currency translation adjustment	(36,752)				(36,646)		(106)
Cash dividends declared - $1.64, $1.44, and $1.31 per share during the year 2018, 2017 and 2016, respectively	(88,166)			(88,166)
Stock-based compensation activity	44,430		36,509			7,921
Issuance of shares under benefit plans (in shares)		843,000
Purchase of shares for treasury	(342,003)					(342,003)
Purchase of shares for treasury (in shares)		(5,862,000)
Ending Balance at Dec. 31, 2016	712,206	$ 9,858	309,417	2,236,071	(329,037)	(1,514,832)	729
Ending Balance (in shares) at Dec. 31, 2016		65,674,000
Increase (Decrease) in Stockholders' Equity
Net income	247,475			247,503			(28)
Unrecognized amounts from defined benefit pension plans, net of tax	10,662				10,662
Unrealized gain on derivatives designated and qualifying as cash flow hedges, net of tax	288				288
Currency translation adjustment	71,016				70,901		115
Cash dividends declared - $1.64, $1.44, and $1.31 per share during the year 2018, 2017 and 2016, respectively	(95,355)			(95,355)
Stock-based compensation activity	29,325		24,892			4,433
Issuance of shares under benefit plans (in shares)		470,000
Purchase of shares for treasury	(43,164)					(43,164)
Purchase of shares for treasury (in shares)		(481,000)
Ending Balance at Dec. 31, 2017	$ 932,453	$ 9,858	334,309	2,388,219	(247,186)	(1,553,563)	816
Ending Balance (in shares) at Dec. 31, 2017	65,662,546	65,663,000
Increase (Decrease) in Stockholders' Equity
Net income	$ 286,993			287,066			(73)
Unrecognized amounts from defined benefit pension plans, net of tax	3,228				3,228
Unrealized gain on derivatives designated and qualifying as cash flow hedges, net of tax	819				819
Currency translation adjustment	(50,693)				(50,600)		(93)
Cash dividends declared - $1.64, $1.44, and $1.31 per share during the year 2018, 2017 and 2016, respectively	(106,802)			(106,802)
Stock-based compensation activity	23,244		21,956			1,288
Issuance of shares under benefit plans (in shares)		158,000
Purchase of shares for treasury	$ (201,650)					(201,650)
Purchase of shares for treasury (in shares)	(2,251,350)	(2,275,000)
Stockholders' Equity, Other	$ 0		4,043	(4,043)
Ending Balance at Dec. 31, 2018	$ 887,592	$ 9,858	$ 360,308	$ 2,564,440	$ (293,739)	$ (1,753,925)	$ 650
Ending Balance (in shares) at Dec. 31, 2018	63,545,878	63,546,000