Restructuring Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Restructuring Reserve [Roll Forward]
Reserve balance at June 30, 2014	$ 0.0
Restructuring charges	29.1	$ 0.0	$ 0.0
Cash payments	(10.9)
Payments from qualified pension plan associated with restructuring charges	(8.3)
Non-cash asset impairment charges and other	(7.6)
Reserve balance at June 30, 2015	2.3	0.0
Personnel-related costs
Restructuring Reserve [Roll Forward]
Restructuring charges	12.7	0.0	0.0
Cash payments	(2.5)
Payments from qualified pension plan associated with restructuring charges	(8.3)
Non-cash asset impairment charges and other	(0.4)
Reserve balance at June 30, 2015	2.3
Site closure costs
Restructuring Reserve [Roll Forward]
Restructuring charges	3.0	0.0	0.0
Cash payments	(0.4)
Non-cash asset impairment charges and other	(2.6)
Material development program exit costs
Restructuring Reserve [Roll Forward]
Restructuring charges	13.4	$ 0.0	$ 0.0
Cash payments	(8.0)
Non-cash asset impairment charges and other	$ (5.4)