Cash and Investments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 28, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 87,344	$ 92,853
Gross Unrealized Gains	26	22
Gross Unrealized Losses	(9)	(13)
Estimated Fair Market Value	87,361	92,862
Cash and Cash equivalents [Member] | Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	37,584	43,139
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	37,584	43,139
Cash and Cash equivalents [Member] | Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	403	876
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	403	876
Cash and Cash equivalents [Member] | Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		750
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Market Value		750
Short-term investments [Member] | Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	999
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Market Value	999
Short-term investments [Member] | U.S. Treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,008	5,036
Gross Unrealized Gains	1	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	5,009	5,036
Short-term investments [Member] | U.S. Government agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,412	11,980
Gross Unrealized Gains	6	4
Gross Unrealized Losses	(2)	(4)
Estimated Fair Market Value	13,416	11,980
Short-term investments [Member] | Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,228	9,756
Gross Unrealized Gains	5	11
Gross Unrealized Losses	(1)	(4)
Estimated Fair Market Value	8,232	9,763
Short-term investments [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,710	21,316
Gross Unrealized Gains	14	7
Gross Unrealized Losses	(6)	(5)
Estimated Fair Market Value	$ 21,718	$ 21,318