Other Long Term Liabilities - Summary of Other Long Term Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Other Liabilities Disclosure [Abstract]
Pension obligation	$ 6.1	$ 6.0
Other	0.5	0.3
Total other long term liabilities	$ 6.6	$ 6.3

Amount of liability, recognized in statement of financial position, for defined benefit pension plan, classified as noncurrent. Excludes other postretirement benefit plan.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant