Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
James Horwich [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 251	$ 226	$ 728	$ 567
Robert E Shaw [Member]
Related Party Transaction [Line Items]
Ownership of Common Stock, Percentage	7.40%		7.40%
Voting Interest of Common Stock, Percentage	3.50%		3.50%
Related Party Transaction, Purchases from Related Party	$ 2,119	$ 1,844	$ 5,776	$ 5,478
Related Party Transaction, Purchases from Related Party, Percentage	2.70%	2.50%	2.50%	2.50%
Robert P Rothman [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 69	$ 67	$ 204	$ 200