Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent, Period Start			$ 1,323,073	$ 1,251,582	$ 1,251,582
Net Income	69,079	56,454	122,515	114,865	276,005
Dividends			(98,862)		(186,828)
Issuance of shares under incentive stock plans			3,980		13,451
Stock-based compensation			9,460		16,181
Excess tax benefit on stock-based compensation			4,234		5,681
Repurchase of common shares			(7,783)		(7,909)
Net gain (loss) from pension and postretirement plans	3,401	2,094	6,541	4,188	(46,263)
Foreign currency translation adjustment	(8,081)	7,442	(2,255)	7,729	3,546
Joint venture cash flow hedges	(1,998)	699	(793)	132	(2,373)
Stockholders' Equity Attributable to Parent, Period End	1,360,110		1,360,110		1,323,073
Dividends [Abstract]
Common Stock, Dividends, Per Share, Declared	$ 0.40	$ 0.36	$ 0.80	$ 0.72	$ 1.52
Common Stock Including Additional Paid in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent, Period Start			630,286	602,882	602,882
Shares Issued, Period Start			122,035,177	121,023,140	121,023,140
Issuance of shares under incentive stock plans			3,980		13,451
Issuance of shares under incentive stock plan, Shares			672,859		1,220,731
Stock-based compensation			9,460		16,181
Excess tax benefit on stock-based compensation			4,234		5,681
Repurchase of common shares			(7,783)		(7,909)
Stock Repurchased During Period, Shares			(169,757)		(208,694)
Shares Issued, Period End	122,538,279		122,538,279		122,035,177
Stockholders' Equity Attributable to Parent, Period End	640,177		640,177		630,286
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent, Period Start			806,235	717,058	717,058
Net Income			122,515		276,005
Dividends			(98,862)		(186,828)
Stockholders' Equity Attributable to Parent, Period End	829,888		829,888		806,235
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent, Period Start			(113,448)	(68,358)	(68,358)
Net gain (loss) from pension and postretirement plans			6,541		(46,263)
Foreign currency translation adjustment			(2,255)		3,546
Joint venture cash flow hedges			(793)		(2,373)
Stockholders' Equity Attributable to Parent, Period End	$ (109,955)		$ (109,955)		$ (113,448)