Derivatives and Hedging Activities - Schedule of Changes in AOCI Associated with Derivative Hedging Activities (Details) - Cash flow hedges - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning	$ (21.8)	$ (28.5)	$ 7.6
Current period changes in fair value, net of tax	5.8	(20.8)	(46.0)
Reclassification to earnings, net of tax	13.7	27.5	9.9
Balance, ending	$ (2.3)	$ (21.8)	$ (28.5)