Note 8 - Stockholders' Equity (Deficiency) - Summary of Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Outstanding, number of options (in shares)	5,219,163
Granted (in shares)
Exercised (in shares)	(1,215,000)
Exercised, weighted average exercise price (in dollars per share)	$ (0.50)
Expired, unexercised (in shares)	(4,004,163)
Expired, unexercised, weighted average exercise price (in dollars per share)	$ (0.51)
Outstanding, number of options (in shares)		5,219,163
Outstanding, weighted average exercise price (in dollars per share)		$ 0.48
Warrants with June 15, 2018 Expiration Date [Member]
Granted (in shares)		2,323,779
Granted, weighted average exercise price (in dollars per share)		$ 0.49
Exercised (in shares)		(121,111)
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
Granted, weighted average exercise price (in dollars per share)		$ 0.52
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
Granted, weighted average exercise price (in dollars per share)		$ 0.52
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