Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Inventory Disclosure [Abstract]
Inventories at FIFO, net of reserves	$ 362.3		$ 456.7
Less: LIFO reserve	(93.2)		(90.3)
Total inventories at LIFO, net of reserves	269.1		366.4
LIFO expense	$ 2.9	$ 2.9