Net Defined Benefit and Post-Retirement Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 28, 2013	Jun. 29, 2012	Jun. 28, 2013	Jun. 29, 2012
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,169	$ 1,072	$ 3,598	$ 3,281
Interest cost	1,276	1,325	3,891	4,016
Plan curtailment				(161)
Expected return on plan assets	(1,388)	(1,316)	(4,235)	(3,982)
Amortization of prior service cost	41	40	121	120
Recognized actuarial loss	682	621	2,045	1,863
Net periodic benefit cost	1,780	1,742	5,420	5,137
Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	40	55	120	165
Amortization of prior service cost	1	1	3	3
Recognized actuarial loss	15	21	45	63
Net periodic benefit cost	$ 56	$ 77	$ 168	$ 231