Post-Retirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2015	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer	$ 0.6	$ 1.8
Contributions to the Compensation Plan by the employer in remainder of fiscal year 2015		0.6
Unfunded Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 7.2	$ 7.2