Note 20 - Net Loss Per Share
 12 Months Ended
Dec. 31, 2014
Earnings Per Share [Abstract]  
Earnings Per Share [Text Block]
20. Net Loss Per Share

Basic and diluted net loss per common share was determined by dividing net loss attributable to common stockholders by the weighted average common shares outstanding during the period. The Company’s potentially dilutive shares, which include redeemable convertible preferred stock, common stock options and warrants, have not been included in the computation of diluted net loss per share for all periods as the result would be antidilutive.

The following table presents the computation of basic and diluted net loss per share of common stock:

   
Year Ended December 31,
 
   
2012
   
2013
   
2014
 
                   
Net loss
  $ (10,471,330 )   $ (23,921,563 )   $ (53,305,938 )
Accretion of redeemable convertible preferred stock
    (351,371 )     (884,647 )     (863,226 )
Reverse prior accretion on redeemable preferred stock due to reduction in liquidation value of Series A, B, and C
    —       5,657,638       —  
Preferred stock dividend due to exchanges of preferred shares
    —       (14,726,088 )     —  
                         
Net loss attributable to common stockholders
  $ (10,822,701 )   $ (33,874,660 )   $ (54,169,164 )
                         
Weighted average common shares outstanding, basic and diluted
    198,306       229,865       17,367,665  
                         
Net loss per share attributable to common stockholders, basic and diluted
  $ (54.58 )   $ (147.37 )   $ (3.12 )

The following potentially dilutive securities have been excluded from the computation of diluted weighted average shares outstanding, as they would be antidilutive:

   
Year Ended December 31,
 
   
2012
   
2013
   
2014
 
Redeemable convertible preferred stock
    2,167,143       6,322,747       —  
Stock options outstanding
    366,389       767,510       2,847,097  
Warrants outstanding
    316,184       424,961       82,781