CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 51.1	$ 30.2	$ 118.1	$ 145.7
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)	0.0
Pension and postretirement benefits, net of tax of $(0.5), $(1.2), $(1.6), and $(3.2), respectively	1.7	2.1	5.1	6.7
Net gain (loss) on derivative instruments, net of tax of $(1.0), $(2.7), $12.5, and $(13.2), respectively	3.2	1.3	(35.2)	24.4
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	1.1	3.7	(0.9)	4.0
Other comprehensive income (loss)	6.0	7.1	(31.7)	35.1
Comprehensive income	$ 57.1	$ 37.3	$ 86.4	$ 180.8