Inventories - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Inventory Disclosure [Abstract]
Inventory LIFO reserve		$ 98.2	$ 196.6
Current cost of LIFO inventory		608.5	697.5
Increase in cost of sales		0.0	1.6	$ 0.0
Non-cash excess inventory write-down	$ 22.5	$ 22.5	$ 0.0	$ 0.0