Note 2 - Supplemental Balance-sheet Information (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Amortization of Intangible Assets, Total	$ 91,000	$ 115,000
Depreciation, Depletion and Amortization, Nonproduction, Total	300,000	$ 300,000
Customer-Related Intangible Assets [Member]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	91,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	34,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	91,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	$ 91,000