Changes in Stockholders' Equity and Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jul. 04, 2015	Jul. 02, 2016	Jul. 04, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 305,520
Net loss for the six months ended July 2, 2016			(33,521)
Unrealized loss related to marketable securities, net of tax	$ 1	$ 17	(27)	$ (3)
Reclassification adjustment for losses related to marketable securities included in other income (expense), net of tax	36	(54)	38	234
Translation adjustments, net of tax	(678)	(49)	(441)	(55)
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax			1,899
Stock-based compensation expense related to stock options, ESPP and RSUs			7,798
Defined benefit pension, net of actuarial losses	141	$ 2	141	$ (155)
Ending balance	281,407		281,407
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,187
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax			13
Ending balance	1,200		1,200
Additional Paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			660,089
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of tax			1,886
Stock-based compensation expense related to stock options, ESPP and RSUs			7,798
Ending balance	669,773		669,773
Accumulated deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(352,846)
Net loss for the six months ended July 2, 2016			(33,521)
Defined benefit pension, net of actuarial losses			0
Ending balance	(386,367)		(386,367)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(2,910)
Unrealized loss related to marketable securities, net of tax			(27)
Reclassification adjustment for losses related to marketable securities included in other income (expense), net of tax			38
Translation adjustments, net of tax			(441)
Defined benefit pension, net of actuarial losses			141
Ending balance	$ (3,199)		$ (3,199)