Inventories (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Inventories
LIFO reserve	$ (26.1)	$ (26.1)	$ 143.1
Inventories stated on the FIFO method	304.6	304.6	305.9
Change in LIFO valuation reserve		(186.1)	$ 54.5	$ (50.2)
Lower of cost or market charge related to inventories measured using the LIFO method	$ 69.1
Increase in cost of sale due to liquidation of LIFO inventory quantities		$ 38.7