Cash, Cash Equivalents and Short-term Investments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 27, 2014
Schedule of Available-for-sale Securities [Line Items]
Variable rate demand notes maturity year	2034
Securities amortized cost, Due in one year or less	$ 1,155
Securities fair value, Due in one year or less	1,155
Variable Rate Demand Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities amortized cost, Due in one year or less	200
Securities fair value, Due in one year or less	$ 200