CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 92.1	$ 7.0	$ 115.5	$ 0.8
Other comprehensive income, net of tax
Pension and postretirement benefits, net of tax of $(0.8), $(3.5), $(2.1) and $(14.0), respectively	2.5	5.7	4.6	23.1
Net gain on derivative instruments, net of tax of $(5.6), $(2.4), $(10.4) and $(8.8), respectively	15.0	3.8	23.1	14.6
Foreign currency translation	(1.5)	(4.0)	0.3	(4.7)
Other comprehensive income	16.0	5.5	28.0	33.0
Comprehensive income	$ 108.1	$ 12.5	$ 143.5	$ 33.8