Changes in Stockholders' Equity and Accumulated other Comprehensive loss (Details) (USD $) Share data in Millions, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended
	Feb. 24, 2012	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Balance, December 31, 2011				$ 393,561,000
Net loss for the six months ended June 30, 2012		(12,542,000)	13,031,000	(20,256,000)	23,950,000
Unrealized loss related to marketable securities, net		43,000	(16,000)	(22,000)	(7,000)
Recognized gain on redemption of marketable securities, previously unrealilzed				(78,000)
Translation adjustments		104,000	(130,000)	259,000	(55,000)
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs (net of taxes)				2,027,000
Stock repurchase				(6,970,000)
Retirement of treasury stock				0
Stock-based compensation expense related to stock options, ESPP and RSUs		2,054,000	1,737,000	3,678,000	3,081,000
Balance, June 30, 2012		372,199,000		372,199,000
Stock repurchase program, authorized amount	20,000,000
Shares repurchased		1.1		1.3
Shares repurchased, value		5,400,000		7,000,000
Common stock
Balance, December 31, 2011				1,177,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs (net of taxes)				10,000
Retirement of treasury stock				(13,000)
Balance, June 30, 2012		1,174,000		1,174,000
Additional paid-in capital
Balance, December 31, 2011				627,637,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs (net of taxes)				2,017,000
Retirement of treasury stock				(6,957,000)
Stock-based compensation expense related to stock options, ESPP and RSUs				3,678,000
Balance, June 30, 2012		626,375,000		626,375,000
Treasury stock
Balance, December 31, 2011				0
Stock repurchase				(6,970,000)
Retirement of treasury stock				6,970,000
Balance, June 30, 2012		0		0
Accumulated deficit
Balance, December 31, 2011				(234,908,000)
Net loss for the six months ended June 30, 2012				(20,256,000)
Balance, June 30, 2012		(255,164,000)		(255,164,000)
Accumulated other comprehensive loss
Balance, December 31, 2011				(345,000)
Unrealized loss related to marketable securities, net				(22,000)
Recognized gain on redemption of marketable securities, previously unrealilzed				(78,000)
Translation adjustments				259,000
Balance, June 30, 2012		$ (186,000)		$ (186,000)