Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Company's financial assets and liabilities consist of interest rate swap agreements and marketable securities included in elective deferred compensation plan
Swaps liability	$ (7.5)	$ (8.8)
Fair Value, Measurements, Recurring [Member]
Company's financial assets and liabilities consist of interest rate swap agreements and marketable securities included in elective deferred compensation plan
Swaps liability	(7.5)
Marketable Securities	3.0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Company's financial assets and liabilities consist of interest rate swap agreements and marketable securities included in elective deferred compensation plan
Marketable Securities	3.0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Company's financial assets and liabilities consist of interest rate swap agreements and marketable securities included in elective deferred compensation plan
Swaps liability	(7.5)
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Company's financial assets and liabilities consist of interest rate swap agreements and marketable securities included in elective deferred compensation plan
Swaps liability
Marketable Securities