Inventories (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Components of inventories
Finished goods	$ 292.9	$ 258.0
Work in process	12.7	12.0
Raw materials and repair parts	199.7	180.1
Gross inventories	505.3	450.1
Excess of current cost over last-in, first-out cost	(75.3)	(75.3)
Total inventories, net	$ 430.0	$ 374.8