Note 16 - Stock-based Compensation (Details Textual) - USD ($)		12 Months Ended
May 14, 2013	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		317,323
Share Price		$ 0.30
Proceeds from Stock Options Exercised		$ 0
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total		$ 0
Employee Stock Option [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Employee Stock Option [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Equity Incentive Plan 2009 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	4,133,133

Unrecognized cost of unvested share-based compensation awards.

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Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Price of a single share of a number of saleable stocks of a company.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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