Property, Plant and Equipment, Net - Schedule of Property, Plant and Equipment, Net (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018
Property Plant And Equipment [Abstract]
Land		$ 2.4	$ 2.4
Buildings and improvements		18.9	19.3
Leasehold improvements		30.1	23.0
Equipment		114.0	112.4
Gross property, plant and equipment		165.4	157.1
Less accumulated depreciation		(106.3)	(113.9)
Property, plant and equipment, net	$ 59.1	$ 59.1	$ 43.2	[1]

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.