Certain Significant Estimates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Product Warranty [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 847	$ 695	$ 620
Additions	1,501	1,459	1,156
Deductions	(1,472)	(1,307)	(1,081)
Ending balance	876	847	695
Inventory Valuation Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	471	537	469
Additions	327	470	287
Deductions	(383)	(536)	(219)
Ending balance	415	471	537
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	1,086	900	1,104
Additions	1,758	159	251
Deductions	(1,934)	27	(455)
Ending balance	910	1,086	900
Customer Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	2,151	2,155	2,494
Additions	5,778	5,312	4,747
Deductions	(5,152)	(5,316)	(5,086)
Ending balance	$ 2,777	$ 2,151	$ 2,155