Inventories (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Components of inventories
Finished goods	$ 288.3	$ 222.3
Work in process	14.7	13.3
Raw materials and repair parts	172.5	162.3
Gross inventories	475.5	397.9
Excess of current cost over last-in, first-out cost and other items	(73.6)	(73.9)
Total inventories, net	$ 401.9	$ 324.0