Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 70	$ 37
Interest cost	256	245
Expected return on plan assets	(408)	(417)
Amortization of net loss	210	141
Net periodic cost	$ 128	$ 6