Retirement Benefits - Components of Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Compensation And Retirement Disclosure [Abstract]
Service cost	$ 550	$ 391	$ 1,624	$ 1,204
Interest cost	1,786	1,956	5,312	5,963
Expected return on plan assets	(70)	(60)	(215)	(179)
Amortization of prior service cost	287	352	871	1,055
Amortization of net loss	968	448	2,904	1,345
Net periodic benefit cost	$ 3,521	$ 3,087	$ 10,496	$ 9,388