Cash, Cash Equivalents and Investments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 29, 2014	Dec. 28, 2013
Short-term investments
Amortized Cost	$ 96,840	$ 96,462
Gross Unrealized Gains	185	339
Gross Unrealized Losses	(19)	(13)
Fair Value	97,006	96,788
Corporate debt securities [Member]
Short-term investments
Amortized Cost	36,903	37,422
Gross Unrealized Gains	20	30
Gross Unrealized Losses	(17)	(11)
Fair Value	36,906	37,441
Bank certificates of deposit [Member]
Short-term investments
Amortized Cost	26,350	20,300
Gross Unrealized Gains	12	9
Gross Unrealized Losses	0	(1)
Fair Value	26,362	20,308
United States Treasury securities [Member]
Short-term investments
Amortized Cost	18,921	24,219
Gross Unrealized Gains	24	28
Gross Unrealized Losses	(1)	(1)
Fair Value	18,944	24,246
United States government agency securities [Member]
Short-term investments
Amortized Cost	10,356	10,212
Gross Unrealized Gains	11	11
Gross Unrealized Losses	(1)	0
Fair Value	10,366	10,223
Commercial paper [Member]
Short-term investments
Amortized Cost	2,493	2,492
Gross Unrealized Gains	2	1
Gross Unrealized Losses	0	0
Fair Value	2,495	2,493
Marketable debt securities [Member]
Short-term investments
Amortized Cost	95,023	94,645
Gross Unrealized Gains	69	79
Gross Unrealized Losses	(19)	(13)
Fair Value	95,073	94,711
Marketable equity securities [Member]
Short-term investments
Amortized Cost	1,817	1,817
Gross Unrealized Gains	116	260
Gross Unrealized Losses	0	0
Fair Value	$ 1,933	$ 2,077