Note 7 - Stockholders' Equity (Details Textual) - USD ($)			3 Months Ended
	Mar. 27, 2020	Dec. 13, 2019	Mar. 31, 2020	Mar. 31, 2019
Proceeds from Issuance of Common Stock, Net			$ 3,220,000
Share-based Payment Arrangement, Expense			$ 67,000	$ 81,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)			0
Registered Direct Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	1,000,002
Shares Issued, Price Per Share (in dollars per share)	$ 3.50
Proceeds from Issuance of Common Stock	$ 3,500,000
Payments of Stock Issuance Costs	$ 393,000
At The Market Offering Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)			50,746
Proceeds from Issuance of Common Stock			$ 280,000
Payments of Stock Issuance Costs			$ 167,000
Maximum Offering Price for Issuance of Common Stock		$ 4,400,000
Commission as Percentage of Gross Proceeds		3.00%
Shares Issued, Average Price Per Share (in dollars per share)			$ 5.44
Proceeds from Issuance of Common Stock, Net			$ 114,000