Schedule of Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 27, 2013	Dec. 28, 2012
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,023	$ 1,229
Interest cost	1,514	1,320
Expected return on plan assets	(1,935)	(1,440)
Amortization of prior service cost	43	40
Recognized actuarial (gain) / loss	539	682
Net periodic benefit cost	1,184	1,831
Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	43	40
Amortization of prior service cost	1	1
Recognized actuarial (gain) / loss	(3)	15
Net periodic benefit cost	$ 41	$ 56