Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Service cost	$ 37	$ 31	$ 110	$ 94
Interest cost	244	247	732	740
Expected return on plan assets	(418)	(393)	(1,253)	(1,180)
Amortization of net loss	136	112	409	337
Net periodic cost	$ (1)	$ (3)	$ (2)	$ (9)