CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Common stock	Additional Paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Beginning balances (in shares) at Dec. 31, 2016			121,645
Beginning balances at Dec. 31, 2016		$ 270,430	$ 1,216	$ 680,315	$ (406,945)	$ (4,156)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(70,562)			(70,562)
Unrealized gain (loss) related to marketable securities, net of tax		(73)				(73)
Recognized gain (loss) on redemption of marketable securities, previously unrealized		252				252
Translation adjustments, net of tax		2,620				2,620
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)			2,250
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes		2,818	$ 23	2,795
Stock-based compensation expense related to stock options, ESPP and RSUs	[1]	12,658		12,658
Defined benefit pension, net of actuarial valuation adjustments		(95)				(95)
Ending balances (in shares) at Dec. 30, 2017			123,895
Ending balances at Dec. 30, 2017		217,693	$ 1,239	695,768	(477,862)	(1,452)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(26,322)			(26,322)
Unrealized gain (loss) related to marketable securities, net of tax		41				41
Recognized gain (loss) on redemption of marketable securities, previously unrealized		(18)				(18)
Translation adjustments, net of tax		(1,271)				(1,271)
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)			5,833
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes		26,918	$ 58	26,860
Stock-based compensation expense related to stock options, ESPP and RSUs		13,646		13,646
Defined benefit pension, net of actuarial valuation adjustments		$ 369				369
Ending balances (in shares) at Dec. 29, 2018		129,728	129,728
Ending balances at Dec. 29, 2018		$ 258,457	$ 1,297	736,274	(476,783)	(2,331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		43,493			43,493
Unrealized gain (loss) related to marketable securities, net of tax		42				42
Recognized gain (loss) on redemption of marketable securities, previously unrealized		(53)				(53)
Translation adjustments, net of tax		341				341
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)			4,155
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes		7,082	$ 42	7,040
Stock-based compensation expense related to stock options, ESPP and RSUs		18,899		18,899
Defined benefit pension, net of actuarial valuation adjustments		$ (602)				(602)
Ending balances (in shares) at Dec. 28, 2019		133,883	133,883
Ending balances at Dec. 28, 2019		$ 327,659	$ 1,339	$ 762,213	$ (433,290)	$ (2,603)

[1] In the third quarter of fiscal 2017, in relation to the sale of 100% of the equity of our Hyderabad, India subsidiary and certain assets related to our SimplayLabs testing and certification business, certain stock compensation was accelerated due to a change of control agreement. As a result of this acceleration,the equity effect of stock compensation shown above includes approximately $0.1 million that was charged to restructuring expense as part of the June2017 Plan (see "Note 7 - Restructuring").