Quarterly report pursuant to Section 13 or 15(d)

Stockholders' equity (Public Offerings) (Details)

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Stockholders' equity (Public Offerings) (Details) (USD $)
 6 Months Ended 12 Months Ended
Jun. 30, 2014
Dec. 31, 2013
Stockholders' equity [Abstract]    
Shares issued during period 8,335,000 11,500,000
Shares issued during period, price per share $ 2.40 $ 1.25
Value of shares issued during period $ 20,000,000 $ 14,400,000
Cost of shares issued during period 1,543,000 1,405,000
Placement fee percentage 6.50% 7.00%
Incentive stock options exercised to purchase common shares 39,079  
Total proceeds from stock options exercised to purchase common shares 82,000  
Intrinsic value of stock options exercised to purchase common shares 14,000  
Warrants, number of shares per warrant   0.35
Warrants, number of shares   4,025,000
Exercise price of warrants $ 1.36 $ 1.36
Underwriter, addtional shares purchased   15.00%
Shares issued for warrants exercised 1,161,570  
Value of shares issued for warrants exercised $ 1,580,000