Note 1 - Preparation of Interim Unaudited Consolidated Financial Statements (Details Textual) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 04, 2017	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Service Cost				$ 0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ 89,000	$ 88,000	257,000	$ 262,000
Cash		1,236,000	7,293,000	1,236,000	7,293,000	$ 4,212,000	$ 6,497,000
Net Income (Loss) Attributable to Parent		(305,000)	$ (2,080,000)	(707,000)	(4,957,000)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations				(2,974,000)	$ (3,179,000)
Revolving Credit Facility [Member] | Wells Fargo [Member]
Line of Credit Facility, Remaining Borrowing Capacity		3,400,000		3,400,000
Line of Credit Facility, Current Borrowing Capacity		$ 4,000,000		4,000,000
Subsequent Event [Member]
Net Cash Provided by (Used in) Operating Activities	$ (700,000)
Accounting Standards Update 2017-07 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)				$ 330,000