Supplemental Balance Sheet Information - Prepaid and Other Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Jun. 30, 2016
Balance Sheet Related Disclosures [Abstract]
Prepaid Expense, Current	$ 23.8	$ 29.3
Spare Parts	11.8	10.8
Short-term Investments	0.0	7.0
Other Prepaid Expense, Current	0.0	6.8	[1]
Available-for-sale Securities, Current	18.6	0.0
Other current assets	43.6	35.1
Prepaid Expense and Other Assets, Current	$ 97.8	$ 89.0

[1] The Company transferred certain intellectual property assets between jurisdictions in the year ended June 30, 2016 resulting in a current deferred tax charge asset. This asset was subsequently adjusted as a result of the adoption of a new accounting standard on income tax accounting for intra-entity asset transfer other than inventory. Refer to Note 1 for further details on the adoption of ASU 2016-16.