Note 13 - Warrants - Summary of Warrant Activity (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Warrants outstanding (in shares)		5,894,675	5,069,815
Warrants outstanding (in dollars per share)		$ 6.37	$ 8.18
Warrants issued in connection with the May 2015 equity transaction (in shares)		16,066,371	1,950,000
Warrants issued in connection with the May 2015 equity transaction (in dollars per share)		$ 0.92	$ 2.60
Warrants expired during 2015 (in shares)		(879,163)	(1,125,140)
Warrants expired during 2015 (in dollars per share)		$ 14.94	$ 7.98
Warrants outstanding (in shares)		20,831,883	5,894,675
Warrants outstanding (in dollars per share)		$ 1.88	$ 6.37
Warrants exercised during 2016 (in shares)		(250,000)
Warrants exercised during 2016 (in dollars per share)		$ 0.01
Aggregate intrinsic value of outstanding warrants		$ 534,000
Weighted average remaining contractual terms (Year)	[1]	3 years 116 days

[1] Does not include the remaining Pre-Funded Warrants issued in the June 2016 Offering (totaling 1,850,000 shares underlying these warrants) as these warrants have no expiration date.