Debt (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Debt
Total	$ 1,151.9	$ 1,208.9
Less: unamortized discount	(1.5)	(1.5)
Less: amounts due within one year and short-term borrowings	(86.6)	(83.6)
Total long-term debt	1,063.8	1,123.8
Unsecured revolving credit facility due April 4, 2018
Debt
Total	465.0	525.0
Senior unsecured notes due July 2, 2013
Debt
Total	75.0	75.0
Senior unsecured notes due November 15, 2016
Debt
Total	350.0	350.0
Senior unsecured notes due November 15, 2036
Debt
Total	250.0	250.0
Other notes and revolving credit facilities
Debt
Total	$ 11.9	$ 8.9