Activity and Liability Balances Related to Restructuring Plan (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 28, 2012
Restructuring Cost and Reserve [Line Items]
Charges to costs and expenses	$ 1,572
Fiscal 2012 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring balance, September 28, 2012	382
Charges to costs and expenses	1,572
Cash payments	(993)
Non-cash adjustments	(101)
Restructuring balance, December 28, 2012	860
Fiscal 2012 Restructuring Plan | Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring balance, September 28, 2012	382
Charges to costs and expenses	1,362
Cash payments	(993)
Non-cash adjustments	(97)
Restructuring balance, December 28, 2012	654
Fiscal 2012 Restructuring Plan | Facilities And Other
Restructuring Cost and Reserve [Line Items]
Charges to costs and expenses	210
Non-cash adjustments	(4)
Restructuring balance, December 28, 2012	206
Restructuring Fiscal 2011 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring balance, September 28, 2012	45
Cash payments	(13)
Restructuring balance, December 28, 2012	$ 32