CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 9 months ended Sep. 30, 2016 - 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, 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	213,762		213,762
Cumulative translation adjustment	(6,215)			(6,215)
Net change in retirement obligations (net of tax of $964)	1,856				1,856
Net change on derivatives designated as cash flow hedges (net of tax of $1,872)	3,272					3,272
Issuance of 447,378 shares of common stock from issuance of unvested shares, performance share units and exercise of stock options	23,152	251					22,901
Repurchase of 738,593 shares of common stock	(54,950)						(54,950)
Unvested shares surrendered for tax withholding	(4,899)						(4,899)
Share-based compensation	12,856	12,856
Cash dividends declared - $1.02 per common share outstanding	(77,382)		(77,382)
Balance at Sep. 30, 2016	$ 1,554,743	$ 693,632	$ 1,803,060	$ (99,194)	$ (29,045)	$ (19,346)	$ (794,364)