Note 11 - Stock Options and Restricted Stock - Summary of Restricted Stock Option (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance, Restricted shares (in shares)	836,667
Balance, Restricted shares, Weighted average grant date fair value (in dollars per share)	$ 0.98
Granted, Restricted shares (in shares)	1,473,000	1,042,500
Granted, Restricted shares, Weighted average grant date fair value (in dollars per share)	$ 0.27	$ 1.07
Vested, Restricted shares (in shares)	(43,334)	(58,333)
Vested, Restricted shares, Weighted average grant date fair value (in dollars per share)	$ 1.28	$ 1.11
Forfeited, Restricted shares (in shares)	(260,000)	(147,500)
Forfeited, Restricted shares, Weighted average grant date fair value (in dollars per share)	$ 1.12	$ 0.72
Balance, Restricted shares (in shares)	2,006,333	836,667
Balance, Restricted shares, Weighted average grant date fair value (in dollars per share)	$ 0.55	$ 0.98