Derivative Instruments and Hedging Activities - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivatives used in Net Investment Hedge, Increase (Decrease), Gross of Tax	$ (3.9)	$ 13.6	$ (21.5)	$ 10.0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(2.8)	$ 10.2	(16.2)	$ 7.6
Net accumulated gain related to investment hedges			38.5
Euro Denominated Debt Outstanding [Member]
Derivative [Line Items]
Total long-term debt	$ 811.9		$ 811.9