Post-Retirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Dec. 31, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer	$ 0.6	$ 1.2
Contributions to the Compensation Plan by the employer in remainder of fiscal year 2015		1.1
Unfunded Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 6.9	$ 6.9