Note 11 - Stock-based Compensation (Details) - Stock-Based Compensation Expense is Recognized for Stock Options Granted (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation	$ 459,000	$ 155,000	$ 110,000
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation	114,000	106,000	46,000
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation	$ 345,000	$ 49,000	$ 64,000