Note 13 - Stock-based Compensation - Employee Stock Option Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding (in shares)		45,068	56,131
Outstanding (in dollars per share)		$ 10.79	$ 10.85
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
Granted (in dollars per share)
Exercised (in shares)		(45,005)	(11,063)
Exercised (in dollars per share)		$ 10.79	$ 11.13
Canceled (in shares)		(63)
Canceled (in dollars per share)		$ 11.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		0
Outstanding (in shares)			45,068
Outstanding (in dollars per share)			$ 10.79
Options exercisable (in shares)
Options exercisable (in dollars per share)

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

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