Note 11 - Stock Option Plan - Stock Option Plan (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Outstanding, Shares (in shares)	1,000	3,500
Outstanding, Weighted average exercise price (in dollars per share)	$ 5.74	$ 5.94
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0
Granted, Weighted average exercise price (in dollars per share)	$ 0	$ 0
Exercised, Shares (in shares)	(1,000)	(1,500)
Exercised, Weighted average exercise price (in dollars per share)	$ 5.74	$ 4.58
Forfeited, Shares (in shares)	0	(1,000)
Forfeited, Weighted average exercise price (in dollars per share)	$ 0	$ 8.25
Outstanding, Shares (in shares)	0	1,000
Outstanding, Weighted average exercise price (in dollars per share)	$ 0	$ 5.74

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.

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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 price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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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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