Income Taxes-Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning Balance	$ 52.5	$ 61.5	$ 66.9
Additions based on tax positions related to the current year	0.1	3.3	6.2
Additions for tax positions of prior years	0.0	0.1	0.0
Reductions for tax positions of prior years	(2.7)	(6.8)	(11.0)
Settlements	(47.5)	(5.4)	0.0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(0.2)	(0.2)	(0.6)
Ending Balance	$ 2.2	$ 52.5	$ 61.5