CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 188.5	$ 47.0	$ 11.3
Other comprehensive income (loss), net of tax
Pension and postretirement benefits gain (loss), net of tax of $(26.3), $(27.3) and $52.8, respectively	78.6	45.3	(87.5)
Net gain on derivative instruments, net of tax of $(13.7), $(11.8) and $(4.0), respectively	26.1	19.5	6.7
Foreign currency translation	(1.4)	2.0	(0.9)
Other comprehensive income (loss), net of tax	103.3	66.8	(81.7)
Comprehensive income (loss), net of tax	$ 291.8	$ 113.8	$ (70.4)