Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning Balance Value at Dec. 27, 2014	$ 179,537	$ 24	$ 251,396	$ (69,114)	$ (2,769)
Beginning Balance Shares at Dec. 27, 2014		23,813,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,905			2,905
Employee benefit plan adjustment	(76)				(76)
Foreign currency translation adjustments	(2,344)				(2,344)
Unrealized gain (loss) on investments, net of tax	(13)				(13)
Issuance of common stock under stock-based compensation plans	2,792		2,792
Issuance of common stock under stock-based compensation plans, Shares		521,607
Stock-based compensation expense	6,248		6,248
Repurchases and retirement of common stock under share repurchase plans	$ (1,721)		(1,721)
Repurchases and retirement of common stock under share repurchase plans, Shares	(111,050)	(111,050)
Ending Balance Value at Dec. 26, 2015	$ 187,328	$ 24	258,715	(66,209)	(5,202)
Ending 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	25,070,889
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 30,202			30,202
Adjustment due to adoption of ASU 2016-09 Improvements to Employee Share-Based Payment Accounting | 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