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 2016-16	$ (645)		$ (645)
Adjustment for adoption of ASU | Accounting Standards Update 2018-02	0		6,435		$ (3,411)	$ (3,024)
Balance, December 31, 2017 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]
Net income	312,436		312,436
Cumulative translation adjustment	(25,903)			(25,903)
Net change in retirement obligations (net of tax of $1,417)	3,979				3,979
Net change on derivatives designated as cash flow hedges (net of tax of $1,105)	3,764					3,764
Issuance of 563,193 shares of common stock from issuance of unvested shares, performance share units and exercise of stock options (net of tax of $4,144)	26,793						26,793
Repurchase of 356,590 shares of common stock	(51,660)						(51,660)
Shares surrendered for tax withholding	(11,260)						(11,260)
Share-based compensation	16,035	16,035
Cash dividends declared — $1.29 per common share outstanding	(99,507)		(99,507)
Balance, September 30, 2018 at Sep. 30, 2018	$ 2,060,574	$ 733,843	$ 2,276,634	$ (72,209)	$ (28,586)	$ (13,307)	$ (835,801)