CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock and Additional Paid-In Capital	Retained Earnings	Cumulative Translation Adjustment	Retirement Benefits Adjustments	Cumulative Unrealized Gain (Loss) on Derivatives	Treasury Stock
Balance at Dec. 31, 2015	$ 1,443,291	$ 680,525	$ 1,666,680	$ (92,979)	$ (30,901)	$ (22,618)	$ (757,416)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	271,109		271,109
Cumulative translation adjustment	(62,565)			(62,565)
Net change in retirement obligations, net of tax	3,049				3,049
Net change on derivatives designated as cash flow hedges, net of tax	4,361					4,361
Issuance of shares of common stock from issuance of unvested shares, performance share units and exercise of stock options	30,240	253					29,987
Repurchase of common stock	(54,950)						(54,950)
Share-based compensation	17,337	17,337
Shares surrendered for tax withholding	(4,928)						(4,928)
Cash dividends declared	(103,050)		(103,050)
Balance at Dec. 31, 2016	1,543,894	698,115	1,834,739	(155,544)	(27,852)	(18,257)	(787,307)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	337,257		337,257
Cumulative translation adjustment	113,170			113,170
Net change in retirement obligations, net of tax	(1,302)				(1,302)
Net change on derivatives designated as cash flow hedges, net of tax	4,210					4,210
Issuance of shares of common stock from issuance of unvested shares, performance share units and exercise of stock options	22,935						22,935
Repurchase of common stock	(29,074)						(29,074)
Share-based compensation	19,693	19,693
Shares surrendered for tax withholding	(6,228)						(6,228)
Tax effect of reversal of indefinite assertion on certain intercompany loans	(3,932)			(3,932)
Cash dividends declared	(114,081)		(114,081)
Balance at Dec. 31, 2017	1,886,542	717,808	2,057,915	(46,306)	(29,154)	(14,047)	(799,674)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment for adoption of ASU | Accounting Standards Update 2016-16	(645)		(645)
Adjustment for adoption of ASU | Accounting Standards Update 2018-02	0		6,435		(3,411)	(3,024)
Net income	410,573		410,573
Cumulative translation adjustment	(48,114)			(48,114)
Net change in retirement obligations, net of tax	9,825				9,825
Net change on derivatives designated as cash flow hedges, net of tax	5,006					5,006
Issuance of shares of common stock from issuance of unvested shares, performance share units and exercise of stock options	27,701						27,701
Repurchase of common stock	(173,926)						(173,926)
Share-based compensation	21,432	21,432
Shares surrendered for tax withholding	(11,555)						(11,555)
Cash dividends declared	(132,199)		(132,199)
Balance at Dec. 31, 2018	$ 1,994,640	$ 739,240	$ 2,342,079	$ (94,420)	$ (22,740)	$ (12,065)	$ (957,454)