Note 10 - Shareholders' Equity - Stock Option Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Exercise price (in dollars per share)	$ 2.19	$ 1.58
Risk-free interest rate	1.13%	1.69%
Expected volatility	59.16%	59.20%
Expected life in years (Year)	4 years 91 days	4 years 91 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
Black-Scholes fair value (in dollars per share)	$ 1.03	$ 0.75