CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Pension and post-retirement benefits, tax expense (benefit)	$ 23.2	$ (26.3)	$ (27.3)
Net gain (loss) on derivative instruments, tax expense (benefit)	13.3	(13.7)	(11.8)
Marketable securities gain, tax expense (benefit)	$ 0.0	$ 0.0	$ 0.0