CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Pension and post-retirement benefits gain (loss), tax (expense) benefit	$ (27.3)	$ 52.8	$ 12.0
Net gain (loss) on derivative instruments, tax expense (benefit)	(11.8)	(4.0)	21.7
Unrealized gain on marketable securities, net of tax expense (benefit)	$ 0.0	$ 0.0	$ 0.0