Cash, Cash Equivalents and Investments (Details 2) - USD ($) $ in Thousands	Jul. 04, 2015	Jan. 03, 2015
Short-term investments
Amortized Cost	$ 96,506	$ 90,404
Gross Unrealized Gains	93	91
Gross Unrealized Losses	(39)	(50)
Fair Value	96,560	90,445
Corporate debt securities [Member]
Short-term investments
Amortized Cost	36,272	34,919
Gross Unrealized Gains	8	6
Gross Unrealized Losses	(22)	(31)
Fair Value	36,258	34,894
Bank certificates of deposit [Member]
Short-term investments
Amortized Cost	13,100	21,900
Gross Unrealized Gains	7	10
Gross Unrealized Losses	0	0
Fair Value	13,107	21,910
United States Treasury securities [Member]
Short-term investments
Amortized Cost	33,972	19,375
Gross Unrealized Gains	69	12
Gross Unrealized Losses	(1)	(13)
Fair Value	34,040	19,374
United States government agency securities [Member]
Short-term investments
Amortized Cost	7,157	9,209
Gross Unrealized Gains	2	3
Gross Unrealized Losses	0	(4)
Fair Value	7,159	9,208
Commercial paper [Member]
Short-term investments
Amortized Cost	4,188	3,184
Gross Unrealized Gains	7	4
Gross Unrealized Losses	0	(2)
Fair Value	4,195	3,186
Marketable debt securities [Member]
Short-term investments
Amortized Cost	94,689	88,587
Gross Unrealized Gains	93	35
Gross Unrealized Losses	(23)	(50)
Fair Value	94,759	88,572
Marketable equity securities [Member]
Short-term investments
Amortized Cost	1,817	1,817
Gross Unrealized Gains	0	56
Gross Unrealized Losses	(16)	0
Fair Value	$ 1,801	$ 1,873