Debt, Long-term (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Total long-term debt	$ 784.2		$ 914.5
Less: debt maturing within one year	21.8		5.7
Total long-term debt, less current portion	762.4		908.8
Pollution Control and Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Interest rate percentage, minimum	0.10%
Interest rate percentage, maximum	6.50%
Maturity date, minimum	2013
Maturity date, maximum	2035
Total long-term debt	176.7		176.7
Unamortized discount	0.2		0.2
Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate percentage, minimum	3.95%
Interest rate percentage, maximum	5.20%
Maturity date, minimum	2019
Maturity date, maximum	2022
Total long-term debt	598.2		598.2
Unamortized discount	1.8		1.8
2011 Credit Agreement [Member]
Debt Instrument [Line Items]
Interest rate percentage	1.20%
Debt Instrument, Maturity Year	2016
Total long-term debt	0	[1]	130.0	[1]
Foreign Debt [Member]
Debt Instrument [Line Items]
Interest rate percentage, minimum	0.00%
Interest rate percentage, maximum	10.60%
Maturity date, minimum	2013
Maturity date, maximum	2023
Total long-term debt	$ 9.3		$ 9.6

[1] Letters of credit outstanding under the 2011 Credit Agreement totaled $73.0 million and available funds under this facility were $1,163.0 million at June 30, 2013 (which reflects borrowings under our commercial paper program).