CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (229.6)	$ 1.5	$ 167.0
Other comprehensive income (loss), net of tax
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings	0.0	0.0	(1.0)
Pension and postretirement benefits (losses), net of tax of $(55.3), $13.2 and $23.2, respectively	175.2	(41.0)	(72.9)
Net gain (loss) on derivative instruments, net of tax of $(5.7), $(1.2) and $13.3, respectively	18.0	3.7	(37.6)
Marketable securities gain, net of tax of $0.0, $0.0 and $0.0, respectively	0.0	0.0	0.3
Foreign currency translation	12.5	(8.9)	(0.8)
Other comprehensive income (loss), net of tax	205.7	(46.2)	(112.0)
Comprehensive (loss) income, net of tax	$ (23.9)	$ (44.7)	$ 55.0