Note 3 - Basis of Presentation and Summary of Significant Accounting Policies - Outstanding Dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Anti-dilutive securities (in shares)	11,527,439	3,435,243
Convertible Debt Securities [Member]
Anti-dilutive securities (in shares)	214,385	757,909
Warrant [Member]
Anti-dilutive securities (in shares)	447,721	460,721
Series A Convertible Preferred Stock [Member]
Anti-dilutive securities (in shares)	8,306,278
Employee Stock Option [Member]
Anti-dilutive securities (in shares)	2,555,989	2,207,409
Restricted Stock [Member]
Anti-dilutive securities (in shares)	3,066	9,204