Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances (in shares) at Dec. 29, 2018	129,728,000
Balances at Dec. 29, 2018	$ 1,297	$ 736,274	$ (476,783)	$ (2,331)	$ 258,457
Net income	$ 0	0	15,967	0	15,967
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)	2,808,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes	$ 28	12,995	0	0	13,023
Stock-based compensation related to stock options, ESPP and RSUs	0	7,655	0	0	7,655
Translation adjustments, net of tax	0	0	0	86	86
Unrealized loss related to marketable securities, net of tax	0	0	0	42	42
Recognized gain on redemption of marketable securities, previously unrealized	$ 0	0	0	(53)	(53)
Balances (in shares) at Jun. 29, 2019	132,536,000
Balances at Jun. 29, 2019	$ 1,325	756,924	(460,816)	(2,256)	295,177
Balances (in shares) at Mar. 29, 2019	131,905,000
Balances at Mar. 29, 2019	$ 1,319	751,506	(469,375)	(2,295)	281,155
Net income	$ 0	0	8,559	0	8,559
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)	631,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes	$ 6	1,449	0	0	1,455
Stock-based compensation related to stock options, ESPP and RSUs	0	3,969	0	0	3,969
Translation adjustments, net of tax	$ 0	0	0	39	39
Unrealized loss related to marketable securities, net of tax					0
Recognized gain on redemption of marketable securities, previously unrealized					0
Balances (in shares) at Jun. 29, 2019	132,536,000
Balances at Jun. 29, 2019	$ 1,325	756,924	(460,816)	(2,256)	$ 295,177
Balances (in shares) at Dec. 28, 2019	133,883,000				133,883,000
Balances at Dec. 28, 2019	$ 1,339	762,213	(433,290)	(2,603)	$ 327,659
Net income	$ 0	0	18,796	0	18,796
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)	1,264,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes	$ 12	(2,117)	0	0	(2,105)
Stock-based compensation related to stock options, ESPP and RSUs	0	19,740	0	0	19,740
Translation adjustments, net of tax	$ 0	0	0	40	40
Unrealized loss related to marketable securities, net of tax					0
Recognized gain on redemption of marketable securities, previously unrealized					$ 0
Balances (in shares) at Jun. 27, 2020	135,147,000				135,147,000
Balances at Jun. 27, 2020	$ 1,351	779,836	(414,494)	(2,563)	$ 364,130
Balances (in shares) at Mar. 28, 2020	134,513,000
Balances at Mar. 28, 2020	$ 1,345	769,451	(425,123)	(2,714)	342,959
Net income	$ 0	0	10,629	0	10,629
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes (in shares)	634,000
Common stock issued in connection with the exercise of stock options, ESPP and vested RSUs, net of shares withheld for employee taxes	$ 6	(627)	0	0	(621)
Stock-based compensation related to stock options, ESPP and RSUs	0	11,012	0	0	11,012
Translation adjustments, net of tax	$ 0	0	0	151	151
Unrealized loss related to marketable securities, net of tax					0
Recognized gain on redemption of marketable securities, previously unrealized					$ 0
Balances (in shares) at Jun. 27, 2020	135,147,000				135,147,000
Balances at Jun. 27, 2020	$ 1,351	$ 779,836	$ (414,494)	$ (2,563)	$ 364,130