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	16,381			16,381
Adjustment due to adoption of ASU 2014-09 Revenue from Contracts with Customers, net of tax	725			725
Restructuring of foreign subsidiaries	(80)		3	(83)
Foreign currency translation adjustments	1,987				1,987
Unrealized gain (loss) on investments, net of tax	(89)				(89)
Issuance of common stock under stock-based compensation plans, net of taxes paid	69		69
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		158,028
Stock-based compensation expense	2,338		2,338
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 Mar. 31, 2018	260,727	$ 24	234,793	26,136	(226)
Ending Balance Shares at Mar. 31, 2018		23,890,563
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	$ 2,973			2,973
Foreign currency translation adjustments	647				647
Unrealized gain (loss) on investments, net of tax	55				55
Issuance of common stock under stock-based compensation plans, net of taxes paid	745	$ 1	744
Issuance of common stock under stock-based compensation plans, net of taxes paid, Shares		162,389
Stock-based compensation expense	3,114		3,114
Ending Balance Value at Mar. 30, 2019	$ 320,386	$ 25	$ 251,841	$ 70,375	$ (1,855)
Ending Balance Shares at Mar. 30, 2019	24,534,582	24,534,582