Certain Significant Estimates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Product Warranty
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 702	$ 691	$ 876
Additions	1,736	1,448	1,036
Deductions	(1,750)	(1,437)	(1,221)
Ending balance	688	702	691
Inventory Valuation Reserves
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	456	504	415
Additions	756	383	288
Deductions	(426)	(431)	(199)
Ending balance	786	456	504
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	532	623	910
Additions	322	155	775
Deductions	(371)	(246)	(1,062)
Ending balance	483	532	623
Reserve For Customer Allowances
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	1,550	3,357	2,777
Additions	7,292	6,575	6,608
Deductions	(7,550)	(8,382)	(6,028)
Ending balance	$ 1,292	$ 1,550	$ 3,357