Inventories (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Inventory [Line Items]
Inventories at FIFO, net of reserves	$ 727.0				$ 524.6				$ 727.0	$ 524.6
Less: LIFO reserve	(130.4)				(117.2)				(130.4)	(117.2)
Total inventories at LIFO, net of reserves	596.6				407.4				596.6	407.4
LIFO expense	3.2	$ 3.7	$ 2.9	$ 3.4	(7.3)	$ 3.3	$ 3.5	$ 2.4	13.2	1.9	$ 16.3
LIFO decrement									4.8	12.2
Reduction in LIFO expense									0.6	0.7
United States
Inventory [Line Items]
Less: LIFO reserve	$ (130.4)				$ (117.2)				$ (130.4)	$ (117.2)