Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 69	$ 37	$ 209	$ 110
Interest cost	256	244	767	732
Expected return on plan assets	(407)	(418)	(1,222)	(1,253)
Amortization of net loss	210	136	630	409
Net periodic cost	$ 128	$ (1)	$ 384	$ (2)