Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Inventory Disclosure [Abstract]
Inventories at FIFO, net of reserves	$ 411.5		$ 411.5		$ 456.7
Less: LIFO reserve	(96.9)		(96.9)		(90.3)
Total inventories at LIFO, net of reserves	314.6		314.6		366.4
LIFO expense	$ 3.7	$ 4.3	$ 6.6	$ 7.2