Financial Instruments Measured at Fair Value - Short-Term Investments by Security Type (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,155
Gross Unrealized Gains
Gross Unrealized Losses
Estimated Fair Value	1,155	1,200	[1]
Bank Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000
Gross Unrealized Gains
Gross Unrealized Losses
Estimated Fair Value	1,000
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	155	1,200
Gross Unrealized Gains
Gross Unrealized Losses
Estimated Fair Value	$ 155	$ 1,200

[1] Derived from December 28, 2013 audited financial statements