Inventories (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Components of inventories
Finished goods	$ 228.3	$ 213.5
Work in process	14.4	6.5
Raw materials and repair parts	167.7	137.0
Gross inventories	410.4	357.0
Excess of current cost over last-in, first-out cost	(73.9)	(70.8)
Total inventories	336.5	286.2
Inventories (Textual) [Abstract]
Income from LIFO method	$ 0.1	$ 0.7	$ 1.3