Inventories - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Inventory Disclosure [Abstract]
Inventory LIFO reserve	$ 106.1	$ 98.2
Current cost of LIFO inventory	689.2	608.5
Increase in cost of sales	0.0	0.0	$ 1.6
Non-cash excess inventory write-down	$ 0.0	$ 22.5	$ 0.0