CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 35.5	$ 92.1	$ 67.0	$ 115.5
Other comprehensive (loss) income, net of tax
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings	0.0	0.0	(1.0)	0.0
Pension and postretirement benefits, net of tax of $(0.5), $(0.8), $(1.1), and $(2.1), respectively	1.7	2.5	3.4	4.6
Net (loss) gain on derivative instruments, net of tax of $4.9, $(5.6), $13.6, and $(10.4), respectively	(15.4)	15.0	(38.4)	23.1
Marketable securities gain, net of tax of $0.0, $0.0, $0.0, $0.0, respectively	0.0	0.0	0.3	0.0
Foreign currency translation	(2.7)	(1.5)	(2.0)	0.3
Other comprehensive (loss) income	(16.4)	16.0	(37.7)	28.0
Comprehensive income	$ 19.1	$ 108.1	$ 29.3	$ 143.5