Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Jun. 30, 2017
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 52.5	$ 52.5
Unrecognized Tax Benefits, Including Income Tax Penalties and Interest Accrued	57.5	57.5
Unrecognized tax benefits that impact the effective income tax rate	41.4	41.4
Accrued interest related to uncertain tax positions	5.0	5.0
Interest and penalties subject to indemnification	1.5	1.7
Former Owner [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits Subject to Indemnification	$ 0.7	$ 0.8