Fair Value - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 26, 2014	Sep. 27, 2013	Sep. 28, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers of assets or liabilities between fair value measurement levels	$ 0	$ 0	$ 0
Impairment of investment	7,725,000
Fair value of current maturities of long-term debt	50,000,000	56,250,000
Long-term debt	387,500,000	450,000,000
Augmenix
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of investment	1,400,000
Calypso Medical Technologies Inc
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration liability, reversed		4,900,000
InfiMed Inc
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration liability, reversed	$ 500,000	$ 300,000