Cash and Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 29, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 92,865	$ 109,910
Gross Unrealized Gains	35	10
Gross Unrealized Losses	(10)	(12)
Estimated Fair Market Value	92,890	109,908
Cash and Cash equivalents [Member] | Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	43,085	60,206
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	43,085	60,206
Cash and Cash equivalents [Member] | Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	748	109
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	748	109
Cash and Cash equivalents [Member] | Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,600
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Market Value		2,600
Short-term investments [Member] | Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	950	3,199
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	950	3,199
Short-term investments [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,048	4,996
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	5,048	4,997
Short-term investments [Member] | US Government agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,685	15,567
Gross Unrealized Gains	8	6
Gross Unrealized Losses	(4)	(2)
Estimated Fair Market Value	15,689	15,571
Short-term investments [Member] | Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,546	5,396
Gross Unrealized Gains	11	1
Gross Unrealized Losses	0	(1)
Estimated Fair Market Value	8,557	5,396
Short-term investments [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,803	17,837
Gross Unrealized Gains	16	2
Gross Unrealized Losses	(6)	(9)
Estimated Fair Market Value	$ 18,813	$ 17,830