Schedule of Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 28, 2014	Mar. 29, 2013	Mar. 28, 2014	Mar. 29, 2013
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,026	$ 1,200	$ 2,049	$ 2,429
Interest cost	1,532	1,295	3,046	2,615
Expected return on plan assets	(1,957)	(1,407)	(3,892)	(2,847)
Amortization of prior service cost	42	40	85	80
Recognized actuarial (gain) / loss	538	681	1,077	1,363
Net periodic benefit cost	1,181	1,809	2,365	3,640
Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	43	40	86	80
Amortization of prior service cost	1	1	2	2
Recognized actuarial (gain) / loss	(3)	15	(6)	30
Net periodic benefit cost	$ 41	$ 56	$ 82	$ 112