Inventories (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Components of inventories
Finished goods	$ 308.7	$ 222.3
Work in process	15.2	13.3
Raw materials and repair parts	177.1	162.3
Gross inventories	501.0	397.9
Excess of current cost over last-in, first-out cost and other items	(73.7)	(73.9)
Total inventories, net	$ 427.3	$ 324.0