Lines of Credit and Financing Arrangements (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Lines of Credit and Financing Arrangements (Textual) [Abstract]
Maximum securitization, amount	$ 150.0
Maximum securitization as percentage of net pool balance	100.00%
Program fee	0.60%
Average floating commercial paper rate	0.87%	0.91%
Unused fee	102.00%
Fixed rate of agreement	0.30%
Domestic revolving credit facility [Member]
Line of Credit Facility [Line Items]
Domestic Revolving Credit Facility	650
Borrowings under Domestic Revolving Credit Facility	233.0
Committed standby letters of credit	49.9
Available for future borrowings	367.1
Extended maturity date	Oct. 31, 2016
Maximum increase in borrowings under 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