Inventories (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories at FIFO, net of reserves	$ 541.7		$ 541.7		$ 533.1
Less: LIFO reserve	(121.2)		(121.2)		(115.3)
Total inventories at LIFO, net of reserves	420.5		420.5		$ 417.8
LIFO expense	$ 3.5	$ 4.3	$ 5.9	$ 7.1