CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock and Additional Paid-In Capital	Retained Earnings	Cumulative Translation Adjustment	Retirement Benefits Adjustment	Cumulative Unrealized Gain (Loss) on Derivatives	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment for adoption of ASU | Accounting Standards Update 2016-02	$ 28		$ 28
Balance at Dec. 31, 2018	1,994,640	$ 739,240	2,342,079	$ (94,420)	$ (22,740)	$ (12,065)	$ (957,454)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	110,268		110,268
Cumulative translation adjustment	(3,281)			(3,281)
Net change in retirement obligations (net of tax)	1,262				1,262
Net change on derivatives designated as cash flow hedges (net of tax)	1,227					1,227
Issuance of shares of common stock from issuance of unvested shares, performance share units and exercise of stock options (net of tax)	8,870						8,870
Repurchase of shares of common stock	(51,706)						(51,706)
Shares surrendered for tax withholding	(11,479)						(11,479)
Share-based compensation	5,403	5,403
Balance at Mar. 31, 2019	2,055,232	744,643	2,452,375	(97,701)	(21,478)	(10,838)	(1,011,769)
Balance at Dec. 31, 2019	2,263,229	761,352	2,615,131	(94,353)	(25,809)	(7,183)	(985,909)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	101,998		101,998
Cumulative translation adjustment	(26,456)			(26,456)
Net change in retirement obligations (net of tax)	2,296				2,296
Net change on derivatives designated as cash flow hedges (net of tax)	1,194					1,194
Issuance of shares of common stock from issuance of unvested shares, performance share units and exercise of stock options (net of tax)	2,089						2,089
Repurchase of shares of common stock	(108,907)						(108,907)
Shares surrendered for tax withholding	(12,119)						(12,119)
Share-based compensation	6,463	6,463
Balance at Mar. 31, 2020	$ 2,229,787	$ 767,815	$ 2,717,129	$ (120,809)	$ (23,513)	$ (5,989)	$ (1,104,846)