Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 28, 2018	$ 123,590	$ 57	$ 296,955	$ (136,604)	$ (25,424)	$ (11,394)
Balance, Shares at Dec. 28, 2018		56,615		(27,086)
Issuance of common stock	(2,372)	$ 1	(2,373)
Issuance of common stock, Shares		394
Treasury stock purchased	(1,616)			$ (1,616)
Treasury stock purchased, Shares				(102)
Amortization of restricted stock units and common stock subject to vesting requirements	2,394		2,394
Net income	7,094				7,094
Foreign currency translation	657					657
Balance at Mar. 29, 2019	129,747	$ 58	296,976	$ (138,220)	(18,330)	(10,737)
Ending Balance, Shares at Mar. 29, 2019		57,009		(27,188)
Balance at Dec. 27, 2019	137,614	$ 58	303,707	$ (141,887)	(13,714)	(10,550)
Balance, Shares at Dec. 27, 2019		57,181		(27,425)
Issuance of common stock	(1,962)		(1,962)
Issuance of common stock, Shares		291
Treasury stock purchased	(1,006)			$ (1,006)
Treasury stock purchased, Shares				(73)
Amortization of restricted stock units and common stock subject to vesting requirements	2,469		2,469
Dividends declared	(13)				(13)
Net income	5,527				5,527
Foreign currency translation	(1,830)					(1,830)
Balance at Mar. 27, 2020	$ 140,799	$ 58	$ 304,214	$ (142,893)	$ (8,200)	$ (12,380)
Ending Balance, Shares at Mar. 27, 2020		57,472		(27,498)