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, 2012	$ 1,464,998	$ 551,559	$ 1,113,541	$ 38,639	$ (45,645)	$ (36,397)	$ (156,699)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	255,215		255,215
Cumulative translation adjustment	13,572			13,572
Net change in retirement obligations, net of tax	21,788				21,788
Net change on derivatives designated as cash flow hedges, net of tax	4,738					4,738
Issuance of common stock from issuance of unvested shares, exercise of stock options and deferred compensation plans, net of tax	43,749	43,749
Repurchase of common stock	(167,503)						(167,503)
Share-based compensation	13,350	13,350
Unvested shares surrendered for tax withholding	(1,902)						(1,902)
Cash dividends declared	(75,016)		(75,016)
Balance at Dec. 31, 2013	1,572,989	608,658	1,293,740	52,211	(23,857)	(31,659)	(326,104)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	279,386		279,386
Cumulative translation adjustment	(77,024)			(77,024)
Net change in retirement obligations, net of tax	(16,459)				(16,459)
Net change on derivatives designated as cash flow hedges, net of tax	4,510					4,510
Issuance of common stock from issuance of unvested shares, exercise of stock options and deferred compensation plans, net of tax	23,195	23,195
Repurchase of common stock	(222,487)						(222,487)
Share-based compensation	16,598	16,598
Unvested shares surrendered for tax withholding	(4,952)						(4,952)
Cash dividends declared	(89,305)		(89,305)
Balance at Dec. 31, 2014	1,486,451	648,451	1,483,821	(24,813)	(40,316)	(27,149)	(553,543)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	282,807		282,807
Cumulative translation adjustment	(68,166)			(68,166)
Net change in retirement obligations, net of tax	9,415				9,415
Net change on derivatives designated as cash flow hedges, net of tax	4,531					4,531
Issuance of common stock from issuance of unvested shares, exercise of stock options and deferred compensation plans, net of tax	24,482	14,545					9,937
Repurchase of common stock	(210,551)						(210,551)
Share-based compensation	17,529	17,529
Unvested shares surrendered for tax withholding	(3,259)						(3,259)
Cash dividends declared	(99,948)		(99,948)
Balance at Dec. 31, 2015	$ 1,443,291	$ 680,525	$ 1,666,680	$ (92,979)	$ (30,901)	$ (22,618)	$ (757,416)