Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash paid during the period for income taxes	$ 0.2	$ 4.9
Cash paid for interest	2.8	$ 0.9
Establishment of operating lease right-of-use assets and lease liabilities
Operating lease right-of-use assets	71.3
Accrued liabilities and other long-term liabilities	4.3
ASU 2016-02
Establishment of operating lease right-of-use assets and lease liabilities
Operating lease right-of-use assets	74.5
Operating lease liabilities	$ (78.8)