Cash, Cash Equivalents and Short-term Investments - Short-Term Investments by Security Type (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,155
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Value	1,155	1,200
Bank Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Value	1,000
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	155	1,200
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 155	$ 1,200