Post-Retirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Compensation And Retirement Disclosure [Abstract]
Contributions to the Compensation Plan by the employer	$ 0.9	$ 0.5	$ 1.8	$ 1.0
Contributions to the Compensation Plan by the employer in remainder of fiscal year 2017			$ 1.8