Note 11 - Warrant Liabilities - Outstanding Warrants to Acquire Shares of the Common Stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Number of shares (in shares)	10,066,809	41,924,653
Warrant 1 [Member]
Number of shares (in shares)	10,066,809
Exercise price (in dollars per share)	$ 0.07
Expiration date	Mar. 10, 2026