Debt and Credit Agreements (Details 2) (USD $)	12 Months Ended													12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 5.75% notes due May 15, 2018	Dec. 31, 2010 5.75% notes due May 15, 2018	Dec. 31, 2011 5.125% notes due September 15, 2013	Dec. 31, 2010 5.125% notes due September 15, 2013	Dec. 31, 2011 2.70% notes due October 15, 2015	Dec. 31, 2010 2.70% notes due October 15, 2015	Sep. 30, 2010 2.70% notes due October 15, 2015	Dec. 31, 2011 Other financing payable	Dec. 31, 2010 Other financing payable	Sep. 30, 2010 British pound sterling-denominated notes redeemed on October 27, 2010	Dec. 31, 2011 5.75% notes due May 15, 2018 and 2.70% notes due October 15, 2015
Long-Term Debt
Long-Term Debt	$ 857,358,000	$ 853,735,000		$ 447,613,000	$ 447,312,000	$ 149,705,000	$ 149,544,000	$ 248,681,000	$ 248,350,000		$ 11,359,000	$ 8,529,000
Less: current maturities	(3,558,000)	(4,011,000)
Total Long-term Debt	853,800,000	849,724,000
Interest rate on long-term debt (as a percent)				5.75%		5.125%		2.70%
Weighted-average interest rate (as a percent)											9.40%	7.90%
Principal amount of debt										250,000,000			200,000,000
Cash payments for interest on all debt	46,400,000	59,900,000	61,500,000
Maturities of long-term debt
2013	153,369,000
2014	2,170,000
2015	250,238,000
2016	$ 159,000
Redemption price as a percentage of principal amount of notes														101.00%