Income Taxes (Reconciliation of Income Tax Provision) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Income Taxes [Abstract]
Expected provision/(benefit) at the statutory rate									$ 36.4	$ (23.8)	$ (57.4)
Stock-based compensation									(11.7)	27.9	59.4
State income taxes benefit, net of federal benefit									2.9	(2.1)	(7.4)
Transaction costs not deductible for tax purposes									1.9	1.5	0.7
Change in statutory tax rate									(1.4)	(3.6)	(2.2)
Change in valuation allowance									(10.2)	2.8
Foreign tax rate differential									(3.9)	2.7	0.6
Other, net									4.4	3.1	(2.5)
Provision/(benefit) for income taxes	$ 11.0	$ 0.6	$ 0.2	$ 6.6	$ (13.1)	$ 7.8	$ 11.1	$ 2.7	$ 18.4	$ 8.5	$ (8.8)