Note 8 - Stock Warrants - Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Outstanding (in shares)	1,250,000	1,250,000
Outstanding, weighted average exercise price (in dollars per share)	$ 4	$ 4
Granted (in shares)	549,659		1,250,000
Granted, weighted average exercise price (in dollars per share)	$ 5.36		$ 4
Forfeited (in shares)
Outstanding (in shares)	1,799,659	1,250,000	1,250,000
Outstanding, weighted average exercise price (in dollars per share)	$ 4.42	$ 4	$ 4
Outstanding, weighted average remaining contractual life (Year)	3 years 317 days
Exercisable (in shares)	1,799,659
Exercisable, weighted average exercise price (in dollars per share)	$ 4.42
Exercisable, weighted average remaining contractual life (Year)	3 years 317 days