Note 11 - Shareholders' equity (Details) - Shares Reserved for Future Issuance
Dec. 31, 2014
Feb. 14, 2014
Jan. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Shares Reserved for Future Issuance [Abstract]          
Common share purchase warrants 1,001,000 26,971 769,231 919,000 919,000
Stock options          
Granted and outstanding 1,378,000     1,362,000 241,000
Reserved for future grants 306,137     252,529 74,001
2,685,000     2,534,000 1,234,000