Income Taxes (Reconciliation of Income Tax Provision) (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Taxes [Abstract]
Expected provision at the statutory rate	$ 10.0	$ 7.8
Stock-based compensation	1.5	3.3
State income taxes benefit, net of federal benefit	0.6	0.7
Transaction costs not deductible for tax purposes	0.1
Change in statutory tax rate		(1.7)
Foreign tax rate differential	(2.2)	(0.7)
Change in valuation allowance	(5.7)	(2.4)
Other, net	1.1	(0.4)
Provision for income taxes	$ 5.4	$ 6.6