Note 10 - Share Based Payments - Stock Options Exercisable and Expected to Vest (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Stock options exercisable, Options (in shares)	17,573,330
Stock options exercisable, Weighted average remaining contractual life (Year)	6 years 219 days
Stock options exercisable, Weighted average exercise price (in dollars per share) | $ / shares	$ 0.18
Stock options exercisable, Aggregate intrinsic value | $	$ 2,550
Stock options expected to vest, Options (in shares)	416,667
Stock options expected to vest, Weighted average remaining contractual life (Year)	9 years 47 days
Stock options expected to vest, Weighted average exercise price (in dollars per share) | $ / shares	$ 0.68
Stock options expected to vest, Aggregate intrinsic value | $	$ 397
Options exercisable and expected to vest, Options (in shares)	2,174,000