Note 8 - Options and Warrants to Purchase Common Stock - Summary of the Status and Changes of the Options Granted Under the Stock Option Plans and Other Agreements (Details) - $ / shares		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Outstanding, shares (in shares)		21,277,479
Outstanding, weighted average exercise price (in dollars per share)		$ 0.87
Outstanding, weighted average remaining contractual life (Year)	[1]	4 years 69 days	4 years 94 days
Outstanding, shares (in shares)		21,277,479	21,277,479
Outstanding, weighted average exercise price (in dollars per share)		$ 0.87	$ 0.87
Exercisable, shares (in shares)		20,540,796
Exercisable, weighted average exercise price (in dollars per share)		$ 0.88
Exercisable, weighted average remaining contractual life (Year)	[1]	4 years 40 days

[1] Measured in years