Note 3 - Basis of Presentation and Summary of Significant Accounting Policies - Outstanding Dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Anti-dilutive securities (in shares)	16,529,812	3,231,148	3,212,188	3,231,148
Convertible Debt Securities [Member]
Anti-dilutive securities (in shares)		749,280	213,879	749,280
Warrant [Member]
Anti-dilutive securities (in shares)	14,003,608	460,721	447,721	460,721
Employee Stock Option [Member]
Anti-dilutive securities (in shares)	2,521,605	2,010,409	2,545,989	2,010,409
Restricted Stock [Member]
Anti-dilutive securities (in shares)	4,599	10,738	4,599	10,738