CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 47.0	$ 11.3	$ 58.7
Other comprehensive income (loss), net of tax
Pension and postretirement benefits gain (loss), net of tax of $(27.3), $52.8 and $12.0, respectively	45.3	(87.5)	(20.1)
Net gain (loss) on derivative instruments, net of tax of $(11.8), $(4.0) and $21.7, respectively	19.5	6.7	(36.1)
Unrealized gain on marketable securities, net of tax of $0.0, $0.0 and $0.0, respectively	0.0	0.0	0.1
Foreign currency translation	2.0	(0.9)	(26.9)
Other comprehensive income (loss), net of tax	66.8	(81.7)	(83.0)
Comprehensive income (loss), net of tax	$ 113.8	$ (70.4)	$ (24.3)