CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interests
Cash dividends declared per share	$ 0.47
Beginning balance at Dec. 31, 2018	$ 887,592	$ 9,858	$ 360,308	$ 2,564,440	$ (293,739)	$ (1,753,925)	$ 650
Beginning Balance (in shares) at Dec. 31, 2018		63,546,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	71,466			71,480			(14)
Unrecognized amounts from defined benefit pension plans, net of tax	787				787
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	329				329
Currency translation adjustment	5,136				5,099		37
Cash dividends declared - $0.49 per share and $0.47 per share in 2020 and 2019, respectively	(29,847)			(29,847)
Stock-based compensation activity		148,000
Issuance of shares under benefit plans	4,786		3,302			1,484
Purchase of treasury shares	(75,584)					(75,584)
Purchase of shares for treasury (in shares)		(894,000)
Stockholders' Equity, Other	0		808	(808)
Ending balance at Mar. 31, 2019	$ 864,665	$ 9,858	364,418	2,605,265	(287,524)	(1,828,025)	673
Ending Balance (in shares) at Mar. 31, 2019		62,800,000
Cash dividends declared per share	$ 0.94
Beginning balance at Dec. 31, 2018	$ 887,592	$ 9,858	360,308	2,564,440	(293,739)	(1,753,925)	650
Beginning Balance (in shares) at Dec. 31, 2018		63,546,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	156,910
Unrecognized amounts from defined benefit pension plans, net of tax	1,878
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	28
Currency translation adjustment	9,985
Ending balance at Jun. 30, 2019	$ 846,058	$ 9,858	368,919	2,661,720	(281,850)	(1,913,219)	630
Ending Balance (in shares) at Jun. 30, 2019		61,779,000
Cash dividends declared per share	$ 0.47
Beginning balance at Mar. 31, 2019	$ 864,665	$ 9,858	364,418	2,605,265	(287,524)	(1,828,025)	673
Beginning Balance (in shares) at Mar. 31, 2019		62,800,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	85,444			85,452			(8)
Unrecognized amounts from defined benefit pension plans, net of tax	1,091				1,091
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	(301)				(301)
Currency translation adjustment	4,849				4,884		(35)
Cash dividends declared - $0.49 per share and $0.47 per share in 2020 and 2019, respectively	(29,279)			(29,279)
Stock-based compensation activity		13,000
Issuance of shares under benefit plans	4,919		4,783			136
Purchase of treasury shares	(85,330)					(85,330)
Purchase of shares for treasury (in shares)		(1,034,000)
Stockholders' Equity, Other	0		(282)	282
Ending balance at Jun. 30, 2019	$ 846,058	$ 9,858	368,919	2,661,720	(281,850)	(1,913,219)	630
Ending Balance (in shares) at Jun. 30, 2019		61,779,000
Cash dividends declared per share	$ 0.49
Beginning balance at Dec. 31, 2019	$ 819,077	$ 9,858	389,446	2,736,481	(275,850)	(2,041,763)	905
Beginning Balance (in shares) at Dec. 31, 2019		60,592,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	55,555			55,562			(7)
Unrecognized amounts from defined benefit pension plans, net of tax	609				609
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	(2,369)				(2,369)
Currency translation adjustment	(70,608)				(70,567)		(41)
Cash dividends declared - $0.49 per share and $0.47 per share in 2020 and 2019, respectively	(29,280)			(29,280)
Stock-based compensation activity		152,000
Issuance of shares under benefit plans	4,738		2,826			1,912
Purchase of treasury shares	(109,762)					(109,762)
Purchase of shares for treasury (in shares)		(1,357,000)
Stockholders' Equity, Other	0		(5,176)	5,176
Ending balance at Mar. 31, 2020	$ 667,960	$ 9,858	387,096	2,767,939	(348,177)	(2,149,613)	857
Ending Balance (in shares) at Mar. 31, 2020		59,387,000
Cash dividends declared per share	$ 0.98
Beginning balance at Dec. 31, 2019	$ 819,077	$ 9,858	389,446	2,736,481	(275,850)	(2,041,763)	905
Beginning Balance (in shares) at Dec. 31, 2019		60,592,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	82,568
Unrecognized amounts from defined benefit pension plans, net of tax	(22,427)
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	(1,261)
Currency translation adjustment	$ (56,140)
Purchase of shares for treasury (in shares)	(1,400,000)
Ending balance at Jun. 30, 2020	$ 660,111	$ 9,858	394,692	2,762,833	(355,620)	(2,152,509)	857
Ending Balance (in shares) at Jun. 30, 2020		59,367,000
Cash dividends declared per share	$ 0.49
Beginning balance at Mar. 31, 2020	$ 667,960	$ 9,858	387,096	2,767,939	(348,177)	(2,149,613)	857
Beginning Balance (in shares) at Mar. 31, 2020		59,387,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including non-controlling interests	27,013			26,996			17
Unrecognized amounts from defined benefit pension plans, net of tax	(23,036)				(23,036)
Unrealized gain (loss) on derivatives designated and qualifying as cash flow hedges, net of tax	1,108				1,108
Currency translation adjustment	14,468				14,485		(17)
Cash dividends declared - $0.49 per share and $0.47 per share in 2020 and 2019, respectively	(29,260)			(29,260)
Stock-based compensation activity		25,000
Issuance of shares under benefit plans	5,071		4,754			317
Purchase of treasury shares	$ (3,213)					(3,213)
Purchase of shares for treasury (in shares)	(43,100)	(45,000)
Stockholders' Equity, Other	$ 0		2,842	(2,842)
Ending balance at Jun. 30, 2020	$ 660,111	$ 9,858	$ 394,692	$ 2,762,833	$ (355,620)	$ (2,152,509)	$ 857
Ending Balance (in shares) at Jun. 30, 2020		59,367,000