Note 9 - Warrants to Purchase Common Stock (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Options Outstanding | shares	67,879
Options Granted | shares
Options Expired | shares
Options Outstanding | shares	67,879
Options exercisable at End | shares	66,635
Outstanding at Beginning, Weighted-Average Exercise Price | $ / shares	$ 21.40
Weighted- Average Exercise Price, Granted | $ / shares
Weighted- Average Exercise Price, Expired | $ / shares
Outstanding at Ending, Weighted-Average Exercise Price | $ / shares	$ 21.40
Weighted- Average exercisable at End | $ / shares	$ 21.78
Weighted- Average Remaining Contractual Term, Beginning balance	7 years 2 months 1 day
Weighted- Average Remaining Contractual Term, Ending Balance	6 years 11 months 1 day
Weighted- Average Remaining Contractual Term, exercisable at End	6 years 9 months 26 days
Warrant [Member]
Options Outstanding | shares	78,462
Options Granted | shares
Options Expired | shares	2,475
Options Outstanding | shares	75,987
Options exercisable at End | shares	75,987
Outstanding at Beginning, Weighted-Average Exercise Price | $ / shares	$ 29.55
Weighted- Average Exercise Price, Granted | $ / shares
Weighted- Average Exercise Price, Expired | $ / shares	$ 50.50
Outstanding at Ending, Weighted-Average Exercise Price | $ / shares	30.51
Weighted- Average exercisable at End | $ / shares	$ 30.51
Weighted- Average Remaining Contractual Term, Beginning balance	3 years 5 months 5 days
Weighted- Average Remaining Contractual Term, Ending Balance	3 years 3 months 15 days
Weighted- Average Remaining Contractual Term, exercisable at End	3 years 3 months 15 days