Schedule of Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 27, 2014	Jun. 28, 2013	Jun. 27, 2014	Jun. 28, 2013
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,028	$ 1,169	$ 3,077	$ 3,598
Interest cost	1,545	1,276	4,591	3,891
Expected return on plan assets	(1,977)	(1,388)	(5,869)	(4,235)
Amortization of prior service cost	43	41	128	121
Recognized actuarial (gain) / loss	539	682	1,616	2,045
Net periodic benefit cost	1,178	1,780	3,543	5,420
Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	43	40	129	120
Amortization of prior service cost	1	1	3	3
Recognized actuarial (gain) / loss	(3)	15	(9)	45
Net periodic benefit cost	$ 41	$ 56	$ 123	$ 168