Long-Term Debt and Financing (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Long-Term Debt [Line Items]
Long-term debt, gross	$ 1,000.0		$ 1,000.0
Unaccreted Discount	(0.7)		(0.7)
Long-term debt	999.3		999.3		999.2
Long-term debt, Fair value	1,020.1		1,020.1		1,090.7
Financing Arrangements [Abstract]
Number of days due from receivable			30 days
Sale of receivable	184.7	162.6	365.7	283.2
Proceeds from sale and collection of receivables	205.7	147.3	368.4	325.8
Receivables from sale of receivables	133.7		133.7		147.6
Cash received from financing provider that has not been recognized as revenue	63.2		63.2		30.7
Fixed Rate Note Due 2016 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	300.0		300.0
Long-term debt, Interest rate, Effective percentage	3.12%		3.12%
Long-term debt, interest rate, Stated percentage	3.10%		3.10%
Long-term debt, Maturity date			Mar. 15, 2016
Fixed Rate Note Due 2021 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	300.0		300.0
Long-term debt, Interest rate, Effective percentage	4.63%		4.63%
Long-term debt, interest rate, Stated percentage	4.60%		4.60%
Long-term debt, Maturity date			Mar. 15, 2021
Fixed Rate Note Due 2041 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	400.0		400.0
Long-term debt, Interest rate, Effective percentage	6.01%		6.01%
Long-term debt, interest rate, Stated percentage	5.95%		5.95%
Long-term debt, Maturity date			Mar. 15, 2041
Financing guarantee with recourse [Member]
Financing Arrangements [Abstract]
Guarantor obligations, current carrying value	$ 32.2		$ 32.2
Maximum [Member]
Financing Arrangements [Abstract]
Maximum term for guarantees related to third-party financing arrangements			4 years