Note 11 - Stock Options (Details) - USD ($)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Text Block [Abstract]
Stock option authorized	3,380,000
Options exercisable weighted average remaining contractual term	3 years 15 days
Options outstanding weighted average remaining contractual term	3 years 15 days
Options exercisable, Intrinsic Value	$ 584,216
Options outstanding, Intrinsic Value	584,216
Share-based compensation	113,247	$ 0
Unrecognized share-based compensation cost	$ 2,815,924
Unrecognized weighted-average period	3 years

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of noncash expense for share-based payment arrangement.

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Number of shares authorized for issuance under share-based payment arrangement.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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