Post-Retirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer	$ 0.5	$ 0.6	$ 1.5	$ 1.8
Contributions to the Compensation Plan by the employer in remainder of fiscal year 2016			0.5
Unfunded Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 10.0		$ 10.0