Note 6 - Stockholders' Equity - Stock Option Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Outstanding, Shares (in shares)	19,250
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.32
Granted, Shares (in shares)	10,000	3,250
Granted, Weighted Average Exercise Price (in dollars per share)	$ 5.67
Exercised, Shares (in shares)	0	0
Exercised, Weighted Average Exercise Price (in dollars per share)
Expired and forfeited, Shares (in shares)	(11,750)
Expired and forfeited, Weighted Average Exercise Price (in dollars per share)	$ 12.99
Outstanding, Shares (in shares)	17,500	19,250
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.97	$ 11.32
Exercisable, Shares (in shares)	5,332
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.19

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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