Restructuring (Details) - USD ($)	9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 256,000	$ 997,000
Charges	0	56,000
Cash Payments	(256,000)	(712,000)
Ending Balance	0	341,000
Employee severance and benefits [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0	383,000
Charges	0	45,000
Cash Payments	0	(428,000)
Ending Balance	0	0
Facility termination costs [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	249,000	583,000
Charges	0	0
Cash Payments	(249,000)	(249,000)
Ending Balance	0	334,000
Other [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	7,000	31,000
Charges	0	11,000
Cash Payments	(7,000)	(35,000)
Ending Balance	$ 0	$ 7,000