Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings / (Accumulated Deficit)	Accumulated Other Comprehensive Income
Beginning Balance Value at Dec. 26, 2015	$ 187,328	$ 24	$ 258,715	$ (66,209)	$ (5,202)
Beginning Balance Shares at Dec. 26, 2015		24,224,286
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,035			44,035
Employee benefit plan adjustment	(17)				(17)
Foreign currency translation adjustments	(869)				(869)
Unrealized gain (loss) on investments, net of tax	42				42
Issuance of common stock under stock-based compensation plans	6,625	$ 1	6,624
Issuance of common stock under stock-based compensation plans, Shares		846,603
Stock-based compensation expense	7,666		7,666
Excess tax benefit related to stock options	(1,036)		(1,036)
Ending Balance Value at Dec. 31, 2016	243,774	$ 25	271,969	(22,174)	(6,046)
Ending Balance Shares at Dec. 31, 2016		25,070,889
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,202			30,202
Adjustment due to adoption of ASU | Accounting Standards Update 2016-09 [Member]	1,224		139	1,085
Employee benefit plan adjustment	(160)				(160)
Foreign currency translation adjustments	4,170				4,170
Unrealized gain (loss) on investments, net of tax	(88)				(88)
Issuance of common stock under stock-based compensation plans	1,441	$ 1	1,440
Issuance of common stock under stock-based compensation plans, Shares		623,681
Stock-based compensation expense	8,819		8,819
Repurchases and retirement of common stock under share repurchase plans	$ (26,999)		(26,999)
Repurchases and retirement of common stock under share repurchase plans, Shares	(1,065,848)	(1,065,848)
Ending Balance Value at Dec. 30, 2017	$ 262,383	$ 26	255,368	9,113	(2,124)
Ending Balance Shares at Dec. 30, 2017	24,628,722	24,628,722
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 57,648			57,648
Adjustment due to adoption of ASU | Accounting Standards Update 2014-09 [Member]	725			725
Employee benefit plan adjustment	(259)				(259)
Foreign currency translation adjustments	(482)				(482)
Unrealized gain (loss) on investments, net of tax	308				308
Restructuring of foreign subsidiaries	(84)			(84)
Issuance of common stock under stock-based compensation plans	218		218
Issuance of common stock under stock-based compensation plans, Shares		514,541
Stock-based compensation expense	11,382		11,382
Stock issued to acquire 4D Technology	4,000		4,000
Stock issued to acquire 4D Technology, Shares		125,117
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)	(896,187)
Ending Balance Value at Dec. 29, 2018	$ 312,852	$ 24	$ 247,983	$ 67,402	$ (2,557)
Ending Balance Shares at Dec. 29, 2018	24,372,193	24,372,193