Note 3 - Summary of Transactions for Stock Options and Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Employee Stock Option [Member]
Number of Shares Outstanding (in shares)	783,718	448,601
Average Exercise Price Outstanding (in dollars per share)	$ 5.33	$ 7.51
Number of Shares Issued (in shares)	117,648	354,253
Average Exercise Price Issued (in dollars per share)	$ 0.17	$ 2.76
Number of Shares Expired (in shares)		(19,136)
Average Exercise Price Expired (in dollars per share)		$ 11.73
Number of Shares Exercised (in shares)	(32,796)
Average Exercise Price Exercised (in dollars per share)	$ 2.63
Number of Shares Outstanding (in shares)	868,570	783,718
Average Exercise Price Outstanding (in dollars per share)	$ 4.73	$ 5.33
Warrant [Member]
Number of Shares Outstanding (in shares)	8,077,477	500,722
Average Exercise Price Outstanding (in dollars per share)	$ 5.14	$ 7.95
Number of Shares Issued (in shares)		7,581,722
Average Exercise Price Issued (in dollars per share)		$ 4.95
Number of Shares Expired (in shares)		(1,967)
Average Exercise Price Expired (in dollars per share)		$ 11.34
Number of Shares Exercised (in shares)	(4,746,405)	(3,000)
Average Exercise Price Exercised (in dollars per share)	$ 4.95	$ 4.95
Number of Shares Outstanding (in shares)	3,331,072	8,077,477
Average Exercise Price Outstanding (in dollars per share)	$ 5.27	$ 5.14
Number of Shares Outstanding (in shares)	868,570