CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 3 months ended Mar. 31, 2017 - 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
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	75,899		75,899
Cumulative translation adjustment	21,050			21,050
Net change in retirement obligations (net of tax of $552)	1,124				1,124
Net change on derivatives designated as cash flow hedges (net of tax of $635)	1,042					1,042
Issuance of 205,965 shares of common stock from issuance of unvested shares, performance share units and exercise of stock options (net of tax of $4,221)	6,074						6,074
Repurchase of 82,000 shares of common stock	(7,562)						(7,562)
Unvested shares surrendered for tax withholding	(5,647)						(5,647)
Share-based compensation	5,431	5,431
Balance at Mar. 31, 2017	$ 1,641,305	$ 703,546	$ 1,910,638	$ (134,494)	$ (26,728)	$ (17,215)	$ (794,442)