Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jun. 30, 2017
Deferred tax assets
Accounts receivable allowances and return reserves	$ 6.8	$ 11.0
Compensation and benefits	44.0	47.2
Indirect benefit of uncertain state and foreign tax positions	6.4	5.1
Investment in foreign subsidiary	62.1	0.0
Tax loss carryforwards	128.5	0.0
All other assets	8.0	7.7
Total deferred tax assets	255.8	71.0
Valuation allowance	(21.1)	0.0
Net deferred tax assets	234.7	71.0
Deferred tax liabilities
Subscription acquisition costs	43.4	86.4
Accumulated depreciation and amortization	600.9	329.8
Deferred gains from dispositions	15.7	29.8
All other liabilities	7.2	9.7
Total deferred tax liabilities	667.2	455.7
Net deferred tax liability	$ 432.5	$ 384.7