Inventories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Inventories at LIFO, Net of Reserves [Line Items]
Inventories at FIFO, net of reserves	$ 456.7				$ 440.3				$ 456.7	$ 440.3
LIFO reserve	(90.3)				(78.0)				(90.3)	(78.0)
Total inventories at LIFO, net of reserves	366.4				362.3				366.4	362.3
LIFO expense	1.3	3.8	4.3	2.9	5.8	5.0	4.6	2.9	12.3	18.3	16.6
United States [Member]
Schedule of Inventories at LIFO, Net of Reserves [Line Items]
LIFO reserve	$ (90.3)				$ (78.0)				$ (90.3)	$ (78.0)