Note 6 - Stockholders' Equity (Deficiency) - Summary of Warrant Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Outstanding, number of options (in shares)	5,219,163
Outstanding, weighted average exercise price (in dollars per share)	$ 0.48
Granted (in shares)
Granted, weighted average exercise price (in dollars per share)
Exercised (in shares)	(15,000)
Exercised, weighted average exercise price (in dollars per share)	$ 0.44
Exercised, weighted average exercise price (in dollars per share)	$ (0.44)
Outstanding, number of options (in shares)	5,204,163	5,219,163
Outstanding, weighted average exercise price (in dollars per share)	$ 0.48	$ 0.48
Warrants with June 15, 2018 Expiration Date [Member]
Granted (in shares)		2,323,779
Exercised (in shares)		(121,111)
Exercised, weighted average exercise price (in dollars per share)		$ (0.43)
Exercised, weighted average exercise price (in dollars per share)		0.43
Warrants with June 15, 2018 Expiration Date [Member] | Minimum [Member]
Granted, weighted average exercise price (in dollars per share)		0.43
Warrants with June 15, 2018 Expiration Date [Member] | Maximum [Member]
Granted, weighted average exercise price (in dollars per share)		$ 0.49
Warrants with September 28, 2018 Expiration Date [Member]
Granted (in shares)		2,887,895
Warrants with September 28, 2018 Expiration Date [Member] | Minimum [Member]
Granted, weighted average exercise price (in dollars per share)		$ 0.44
Warrants with September 28, 2018 Expiration Date [Member] | Maximum [Member]
Granted, weighted average exercise price (in dollars per share)		$ 0.52
Warrants with October 26, 2018 Expiration Date [Member]
Granted (in shares)		128,600
Warrants with October 26, 2018 Expiration Date [Member] | Minimum [Member]
Granted, weighted average exercise price (in dollars per share)		$ 0.44
Warrants with October 26, 2018 Expiration Date [Member] | Maximum [Member]
Granted, weighted average exercise price (in dollars per share)		$ 0.52