Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance Value at Dec. 30, 2017	$ 262,383	$ 26	$ 255,368	$ 9,113	$ (2,124)
Beginning Balance Shares at Dec. 30, 2017		24,628,722
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	45,624			45,624
Adjustment due to adoption of ASU 2014-09 Revenue from Contracts with Customers, net of tax	726			726
Restructuring of foreign subsidiaries	(83)			(83)
Foreign currency translation adjustments	(530)				(530)
Unrealized gain (loss) on investments, net of tax	7				7
Issuance of common stock under stock-based compensation plans, net of taxes paid	706		706
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		483,027
Stock-based compensation expense	8,229		8,229
Repurchases and retirement of common stock under share repurchase plans	(22,987)	$ (2)	(22,985)
Repurchases and retirement of common stock under share repurchase plans, Shares		(896,187)
Ending Balance Value at Sep. 29, 2018	294,075	$ 24	241,318	55,380	(2,647)
Ending Balance Shares at Sep. 29, 2018		24,215,562
Beginning Balance Value at Jun. 30, 2018	278,485	$ 24	237,378	43,812	(2,729)
Beginning Balance Shares at Jun. 30, 2018		24,066,368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,568			11,568
Foreign currency translation adjustments	38				38
Unrealized gain (loss) on investments, net of tax	44				44
Issuance of common stock under stock-based compensation plans, net of taxes paid	728		728
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		149,194
Stock-based compensation expense	3,212		3,212
Ending Balance Value at Sep. 29, 2018	294,075	$ 24	241,318	55,380	(2,647)
Ending Balance Shares at Sep. 29, 2018		24,215,562
Beginning Balance Value at Dec. 29, 2018	$ 312,852	$ 24	247,983	67,402	(2,557)
Beginning Balance Shares at Dec. 29, 2018	24,372,193	24,372,193
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 11,114			11,114
Foreign currency translation adjustments	(68)				(68)
Unrealized gain (loss) on investments, net of tax	112				112
Issuance of common stock under stock-based compensation plans, net of taxes paid	2,049	$ 1	2,048
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		470,766
Stock-based compensation expense	9,713		9,713
Ending Balance Value at Sep. 28, 2019	$ 335,772	$ 25	259,744	78,516	(2,513)
Ending Balance Shares at Sep. 28, 2019	24,842,959	24,842,959
Beginning Balance Value at Jun. 29, 2019	$ 328,980	$ 25	256,503	74,305	(1,853)
Beginning Balance Shares at Jun. 29, 2019		24,828,384
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,211			4,211
Foreign currency translation adjustments	(671)				(671)
Unrealized gain (loss) on investments, net of tax	11				11
Issuance of common stock under stock-based compensation plans, net of taxes paid	(158)		(158)
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		14,575
Stock-based compensation expense	3,399		3,399
Ending Balance Value at Sep. 28, 2019	$ 335,772	$ 25	$ 259,744	$ 78,516	$ (2,513)
Ending Balance Shares at Sep. 28, 2019	24,842,959	24,842,959