Changes in Stockholders' Equity and Accumulated other Comprehensive Loss (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		0 Months Ended	3 Months Ended	0 Months Ended	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012	Feb. 24, 2012 Share Repurchase Program approved on Feb 24, 2012	Mar. 30, 2013 Share Repurchase Program approved on Feb 24, 2012	Feb. 27, 2013 Share Repurchase Program approved on Feb 27, 2013	Mar. 30, 2013 Share Repurchase Program approved on Feb 27, 2013	Mar. 30, 2013 Common stock	Mar. 30, 2013 Additional paid-in capital	Mar. 30, 2013 Treasury stock	Mar. 30, 2013 Accumulated deficit	Mar. 30, 2013 Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 357,550,000						$ 1,155,000	$ 621,170,000	$ 0	$ (264,514,000)	$ (261,000)
Net loss for the period	1,890,000	(7,714,000)								1,890,000
Unrealized loss related to marketable securities, net	(75,000)	(65,000)									(75,000)
Translation adjustments	(165,000)	155,000									(165,000)
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs (net of taxes)	1,356,000						6,000	1,350,000
Stock repurchase	(2,452,000)								(2,452,000)
Retirement of treasury stock	0						(6,000)	(2,446,000)	2,452,000	0	0
Stock-based compensation expense related to stock options, ESPP and RSUs	1,912,000							1,912,000
Ending balance	360,016,000						1,155,000	621,986,000	0	(262,624,000)	(501,000)
Stock repurchase program, authorized amount			20,000,000		20,000,000
Shares repurchased				0.6		0
Shares repurchased, value				$ 2,500,000