Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 75	$ 71
Interest cost	215	247
Expected return on plan assets	(372)	(351)
Amortization of prior service cost	13	12
Amortization of net loss	215	210
Net periodic benefit cost	$ 146	$ 189