Inventories (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Components of inventories
Finished goods	$ 345.7	$ 251.4
Work in process	17.6	11.8
Raw materials and repair parts	199.7	188.9
Gross inventories	563.0	452.1
Excess of current cost over last-in, first-out cost	(72.7)	(73.3)
Total inventories, net	$ 490.3	$ 378.8