Lines of Credit and Financing Arrangements (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended				3 Months Ended	12 Months Ended
	Dec. 31, 2011	Nov. 18, 2011	Dec. 31, 2010	Nov. 29, 2010	Sep. 30, 2011 Domestic revolving credit facility [Member]	Dec. 31, 2011 Domestic revolving credit facility [Member]	Dec. 31, 2011 Senior Notes [Member]	Dec. 31, 2010 Senior Notes [Member]	May 31, 2010 Senior Notes [Member]
Lines of Credit and Financing Arrangements (Textual) [Abstract]
Fixed interest rate for senior unsecured notes							4.90%
Senior unsecured notes							$ 200.0	$ 200.0	$ 200.0
Default long term debt description of violation or event of default of revolving credit facility							The indenture governing the notes contains covenants limit our ability and the ability of the subsidiary guarantors to: create or incur certain liens; enter into certain sale and leaseback transactions; enter into certain mergers, consolidations and transfers of substantially all of our assets; and transfer certain properties.indenture also contains a cross default provision which is triggered if we default on other debt of at least $75 million in principal which is then accelerated, and such acceleration is not rescinded within 30 days of the notice date
Minimum principal amount accelerated							75
Line of Credit Facility [Line Items]
Domestic Revolving Credit Facility						650
Extended maturity date						October 21, 2016
Maximum domestic revolving credit facility						100
Indebtedness to Adjusted EBITDA Ratio					3.5:1.0
Cash Flow to Net Interest Expense ratio					3.0:1.0
Maximum securitization, amount	$ 150.0	$ 100.0		$ 150.0
Average floating commercial paper rate	0.91%		1.06%
Program fee	0.60%
Basis of unused fee	Unused fee is based on 102% of the maximum available amount less the beneficial interest sold and calculated at a 0.30% fixed rate throughout the term of the agreement
Fixed rate of agreement	0.30%