Note 12 - Net Loss Per Share Attributable to Common Stockholders - Calculation of Basic and Diluted Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net loss	$ (5,260)	$ (6,548)	$ (12,236)	$ (13,105)
Series B and C preferred dividend				(339)
Net loss attributable to common stockholders – diluted calculation	$ (5,260)	$ (6,548)	$ (12,236)	$ (13,444)
Shares used to compute net loss per share - basic and diluted (in shares)	16,249,032	7,141,189	12,748,665	6,038,001
Net loss per share - basic and diluted (in dollars per share)	$ (0.32)	$ (0.92)	$ (0.96)	$ (2.23)

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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The amount of preferred stock dividends that is an adjustment to net income apportioned to common stockholders.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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