Note 14 - Stock-based Compensation - Summary of Outstanding Options (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Outstanding (in shares) | shares	3,121,200
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 3.50
Issued (in shares) | shares	50,000
Issued, weighted average exercise price (in dollars per share) | $ / shares	$ 3.13
Exercised (in shares) | shares	(469,701)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 2.59
Cancelled/Forfeited (in shares) | shares	(14,000)
Cancelled/Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 3.13
Outstanding (in shares) | shares	2,687,499
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 3.66
Outstanding, weighted average remaining contractual life (Year)	2 years 73 days
Outstanding, aggregate intrinsic value | $	$ 14,386,956
Exercisable (in shares) | shares	1,076,836
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 3.50
Exercisable, weighted average remaining contractual life (Year)	1 year 182 days
Exercisable, aggregate intrinsic value | $	$ 5,930,463