CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in	Treasury Stock	Retained	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2012		132,349,534		36,518,656
Beginning Balance at Dec. 31, 2012	$ 1,276,830	$ 1,323	$ 381,348	$ (349,388)	$ 1,297,111	$ (53,564)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends ($0.13 in 2013, $ 0.20 in 2014 and $0.28 in 2015)	(12,644)				(12,644)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(21,232)		(11,815)	$ (9,417)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				586,175
Stock based compensation	21,896		21,896
Net income	292,235				292,235
Translation adjustment	5,345					5,345
Unrealized gain (loss) on interest rate swap contracts, net of tax	(195)					(195)
Change in pension and post-retirement benefit plans, net of tax	644					644
Stock repurchase, shares (in shares)				(507,105)
Stock repurchase, value	(32,998)			$ (32,998)
Ending Balance at Dec. 31, 2013	1,585,259	$ 1,323	415,059	$ (372,969)	1,576,702	(34,856)
Ending Balance (in shares) at Dec. 31, 2013		132,349,534		36,439,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends ($0.13 in 2013, $ 0.20 in 2014 and $0.28 in 2015)	(19,246)				(19,246)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(17,461)		(9,997)	$ (7,464)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				711,247
Stock based compensation	23,475		23,475
Net income	351,680				351,680
Translation adjustment	(111,776)					(111,776)
Unrealized gain (loss) on foreign exchange contracts, net of tax ($ 61 in 2013, and $31 in 2014)	(23)					(23)
Unrealized gain (loss) on interest rate swap contracts, net of tax	(210)					(210)
Change in pension and post-retirement benefit plans, net of tax	(12,621)					(12,621)
Stock repurchase, shares (in shares)				(346,800)
Stock repurchase, value	(26,757)			$ (26,757)
Ending Balance at Dec. 31, 2014	1,807,242	$ 1,323	448,531	$ (392,262)	1,909,136	(159,486)
Ending Balance (in shares) at Dec. 31, 2014		132,349,534		36,075,139
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends ($0.13 in 2013, $ 0.20 in 2014 and $0.28 in 2015)	(26,963)				(26,963)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(2,007)		(2,918)	$ (4,925)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				450,738
Stock based compensation	23,713		23,713
Net income	398,628
Translation adjustment	(132,899)					(132,899)
Unrealized gain (loss) on foreign exchange contracts, net of tax ($ 61 in 2013, and $31 in 2014)	(66)					(66)
Unrealized gain (loss) on interest rate swap contracts, net of tax	(678)					(678)
Change in pension and post-retirement benefit plans, net of tax	16,410					16,410
Stock repurchase, shares (in shares)				(4,889,027)
Stock repurchase, value	(387,787)			$ (387,787)
Ending Balance at Dec. 31, 2015	$ 1,699,607	$ 1,323	$ 469,326	$ (775,124)	$ 2,280,801	$ (276,719)
Ending Balance (in shares) at Dec. 31, 2015		132,349,534		40,513,428