Organization and Significant Accounting Policies - Additional Information 1 (Detail)	3 Months Ended	12 Months Ended
	Sep. 24, 2016 USD ($) Companies	Sep. 24, 2016 USD ($) Companies	Sep. 26, 2015 USD ($)	Sep. 27, 2014 USD ($)	Dec. 30, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Owned percentage in unconsolidated entities (as percent)	50.00%	50.00%
Number of unconsolidated companies | Companies	4	4
Equity income		$ 400,000	$ 400,000	$ 600,000
Investment in unconsolidated companies	$ 500,000	500,000	16,500,000
Non-cash impairment charge	16,600,000	19,367,000	7,272,000	5,870,000
Excess loss insurance that covers any health care claims		700,000
Outstanding derivative instruments	$ 0	0	0
Stock-based compensation		8,356,000	8,315,000	7,678,000
Stock-based compensation after tax		5,300,000	$ 5,300,000	$ 4,900,000
Minimum [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
General liability and vehicle liability insurance policies		250,000
Maximum [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
General liability and vehicle liability insurance policies		350,000
Purishield LLC and Ceregenin LLC [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Owned percentage in unconsolidated entities (as percent)					50.00%
Non-cash impairment charge		$ 16,600,000