Inventories (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Inventory [Line Items]
Inventories at FIFO, net of reserves	$ 591.4		$ 591.4		$ 524.6
Less: LIFO reserve	(123.5)		(123.5)		(117.2)
Total inventories at LIFO, net of reserves	467.9		467.9		407.4
LIFO expense	2.9	$ 3.5	6.3	$ 5.9
United States
Inventory [Line Items]
Less: LIFO reserve	$ (123.5)		$ (123.5)		$ (117.2)