Annual report pursuant to Section 13 and 15(d)

Equity (Details Textual)

v3.6.0.2
Equity (Details Textual) - USD ($)
 1 Months Ended 12 Months Ended
Oct. 04, 2016
Jun. 09, 2015
Feb. 11, 2015
Jul. 10, 2014
Jun. 30, 2014
Mar. 24, 2014
Sep. 30, 2013
Jan. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Equity (Textual)                        
Common stock, par value                 $ 0.001 $ 0.001    
Fair value assumptions, expected volatility rate [1]                   87.00%    
Fair value assumptions, expected term                 2 years 2 years    
Fair value assumptions, expected dividend rate [2]                    
Fair value assumptions, expected risk free interest rate [3]                 0.85% 1.06%    
Stock-based compensation                 $ 4,297,778 $ 7,061,622 $ 6,280,629  
Price per share                 $ 1.96 $ 2.52    
Registration statement description           This Registration Statement contained two prospectuses: (i) a base prospectus which covers the offering, issuance and sale by the Company of up to $200 million of its common stock, preferred stock, warrants and/or units; and (ii) a sales agreement prospectus covering the offering, issuance and sale by us of up to a maximum aggregate offering price of $75,000,000 of its common stock that may be issued and sold under a sales agreement (the " Sales Agreement " ) with MLV & Co. LLC ( " MLV " ) dated March 24, 2014.            
Aggregate offering amount of securities sold to investors           The Company will pay MLV in cash, upon the sale of common stock pursuant to the Sales Agreement, an amount equal to 3.0% of the gross proceeds from the sale of common stock. On April 28, 2014, the Company issued 500 shares and received net proceeds of $6,000 under the Sales Agreement with MLV.            
Gross proceeds from public offering                 $ 7,000,000 $ 15,100,000    
Maximum offering price           $ 75,000,000            
Net proceeds from public offering                 $ 6,800,000 $ 14,700,000    
Number of common shares issued                 3,504,427 5,626,119    
Proceeds from the exercise of options                 $ 18,105 $ 15,680 $ 275,153  
2013 Stock Plan [Member]                        
Equity (Textual)                        
Number of additional shares authorized                 12,750,000 9,250,000    
2013 Equity Incentive Plan [Member]                        
Equity (Textual)                        
Number of additional shares authorized                       1,000,000
Placement agent [Member]                        
Equity (Textual)                        
Exercise price                     $ 9  
Placement agent cash fees               $ 400,000        
Placement agent attorney fees               40,000        
Net proceeds from sale of stock               3,300,000        
Net proceeds from issuance of services               $ 2,900,000        
Minimum [Member]                        
Equity (Textual)                        
Fair value assumptions, expected volatility rate [1]                 61.00%      
Maximum [Member]                        
Equity (Textual)                        
Fair value assumptions, expected volatility rate [1]                 69.00%      
Investor [Member]                        
Equity (Textual)                        
Proceeds from common stock issued   $ 5,000,000                    
Net proceeds from sale of stock   $ 4,480,000                    
Price per share   $ 2.60                    
Number of common shares issued   1,923,078                    
Employees, directors and consultants [Member] | 2013 Stock Plan [Member]                        
Equity (Textual)                        
Number of stock option granted             2,750,000          
Award expiration date             Sep. 09, 2023          
Employees, directors and consultants [Member] | 2013 Equity Incentive Plan [Member]                        
Equity (Textual)                        
Number of stock option granted             450,000          
Award expiration date             Sep. 09, 2023          
Stock Options [Member]                        
Equity (Textual)                        
Stock based compensation expense                 $ 3,600,000 $ 3,400,000 $ 2,400,000  
Number of stock option granted                 2,225,000 1,554,499 1,338,100  
Stock option exercise prices                 $ 0.78 $ 0.78 $ 0.95  
Unrecognized compensation expense                 $ 6,700,000 $ 7,200,000    
Proceeds from the exercise of options                 $ 18,105,000 $ 15,680,000 $ 300,000  
Number of stock option cancelled                 266,485 576,000    
Number of stock exercised                 23,212 20,000 310,400  
Stock Options [Member] | Employees, directors and consultants [Member]                        
Equity (Textual)                        
Number of stock option granted                 2,225,000 1,554,499    
Share-based compensation term                 10 years 10 years 10 years  
Share-based compensation vesting period                 4 years   4 years  
Stock option exercise prices                     $ 0.78  
Fair value assumptions, expected term                 6 years 6 years 6 years  
Fair value assumptions, expected dividend rate                 0.00% 0.00% 0.00%  
Fair value of warrants determined utilizing the Black-Scholes option pricing model                 $ 3,100,000 $ 3,200,000 $ 8,700,000  
Stock Options [Member] | Employees, directors and consultants [Member] | Minimum [Member]                        
Equity (Textual)                        
Exercise price                 $ 1.79 $ 1.79 $ 0.78  
Share-based compensation vesting period                   1 year    
Fair value assumptions, expected discount rate                 1.28% 1.56% 1.77%  
Fair value assumptions, expected volatility rate                 81.45% 85.01% 82.47%  
Stock Options [Member] | Employees, directors and consultants [Member] | Maximum [Member]                        
Equity (Textual)                        
Exercise price                 $ 3.58 $ 3.58 $ 11.95  
Share-based compensation vesting period                   4 years 2 months 1 day    
Fair value assumptions, expected discount rate                 1.97% 1.91% 2.07%  
Fair value assumptions, expected volatility rate                 87.95% 94.89% 87.76%  
Common Stock [Member]                        
Equity (Textual)                        
Common stock issued, shares                 3,504,493      
Proceeds from common stock issued                 $ 6,800,000      
Common Stock [Member] | Placement agent [Member]                        
Equity (Textual)                        
Common stock issued, shares               68,976        
Exercise price               $ 9.00        
Fair value assumptions, expected volatility rate               88.00%        
Fair value assumptions, expected term               5 years        
Fair value assumptions, expected dividend rate               0.00%        
Fair value assumptions, expected risk free interest rate               1.64%        
Fair value of warrants determined utilizing the Black-Scholes option pricing model               $ 300,000        
Warrant [Member]                        
Equity (Textual)                        
Common stock issued, shares                 125,862   551,810  
Proceeds from common stock issued     $ 200,000               $ 200,000  
Stock based compensation expense                 $ 100,000 $ 200,000 $ 100,000  
Number of stock option granted                 45,000      
Exercise price     $ 6.50           $ 1.77   $ 9.00  
Share-based compensation term     4 years                  
Fair value of stock option     $ 3,500,000                  
Fair value assumptions, expected discount rate     1.26%                  
Fair value assumptions, expected volatility rate     72.00%         88.00%        
Fair value assumptions, expected term     4 years         5 years        
Fair value assumptions, expected dividend rate     0.00%         0.00%        
Fair value assumptions, expected risk free interest rate               1.64%        
Stock-based compensation                 $ 100,000 $ 200,000 $ 100,000  
Price per share     $ 4.50               $ 6.00  
Warrants/ Common stock granted                     137,952  
Fair value of warrants determined utilizing the Black-Scholes option pricing model               $ 600,000        
Number of common shares issued     1,736,277           125,862   2,336,658  
Warrants issued to purchase common stock, shares     3,333,333                  
Common shares issued for cashless exercise of warrants                 125,862 1,532,124 2,162,181  
Additional common stock issued for exercise of options and warrants                 23,212 224,153 484,877  
Proceeds from stock options and warrants exercised                 $ 18,105 $ 173,620 $ 435,147  
Number of stock exercised     2,013,360           183,718   2,501,993  
Underwritten offering shares of common stock     4,444,444                  
Warrant [Member] | Placement agent [Member]                        
Equity (Textual)                        
Fair value assumptions, expected volatility rate                     88.00%  
Fair value assumptions, expected term                     5 years  
Fair value assumptions, expected dividend rate                     0.00%  
Fair value assumptions, expected risk free interest rate                     1.64%  
Warrants issued to purchase common stock, shares                     68,976  
Warrant [Member] | Minimum [Member]                        
Equity (Textual)                        
Exercise price                 $ 1.35      
Warrant [Member] | Maximum [Member]                        
Equity (Textual)                        
Exercise price                 $ 1.77      
Warrant [Member] | Consultant [Member]                        
Equity (Textual)                        
Share-based compensation term                     10 years  
Fair value assumptions, expected term                     5 years  
Fair value assumptions, expected dividend rate                 0.00%   0.00%  
Unrecognized compensation expense                     $ 1,500,000  
Warrants/ Common stock granted                 130,000      
Warrants issued to purchase common stock, shares                     285,000  
Fair value of warrants                     $ 2,100,000  
Warrant [Member] | Consultant [Member] | Minimum [Member]                        
Equity (Textual)                        
Exercise price                 $ 0.98      
Share-based compensation term                 5 years      
Fair value of stock option                 $ 116,000      
Fair value assumptions, expected discount rate                 1.13%   1.56%  
Fair value assumptions, expected volatility rate                 79.79%   82.47%  
Fair value assumptions, expected term                 5 years      
Warrant [Member] | Consultant [Member] | Maximum [Member]                        
Equity (Textual)                        
Exercise price                 $ 1.77      
Share-based compensation term                 10 years      
Fair value assumptions, expected discount rate                 1.20%   1.66%  
Fair value assumptions, expected volatility rate                 84.84%   87.76%  
Fair value assumptions, expected term                 10 years      
Warrant [Member] | Investor [Member]                        
Equity (Textual)                        
Warrants issued to purchase common stock, shares                     137,952  
Restricted Stock [Member]                        
Equity (Textual)                        
Number of shares of restricted stock, granted                 60,700      
Stock based compensation expense                 $ 600,000 $ 3,400,000 $ 3,700,000  
Number of shares of restricted stock for prior years, granted                 21,000      
Restricted Stock [Member] | Consultant [Member]                        
Equity (Textual)                        
Number of shares of restricted stock, granted                 250,700 479,651    
Restricted stock granted value                 $ 400,000 $ 2,300,000    
Restricted stock granted not been issued                 60,700 329,651    
Description restricted stock                 Of the 250,700 restricted share awards granted in 2016, 60,700 shares vested at the date of grant, 150,000 shares vest over a six-month period and 40,000 shares vest over 2 years. Of the 479,651 restricted share awards granted in 2015, 329,651 shares vested at the date of grant and 150,000 shares vest over a six-month period.    
Restricted Stock [Member] | Employees, directors and consultants [Member]                        
Equity (Textual)                        
Number of shares of restricted stock, granted                   152,499 633,041  
Restricted stock granted value                   $ 800,000 $ 4,900,000  
Restricted stock granted not been issued                     202,497  
Number of stock option cancelled                   126,265 50,000  
Description restricted stock                     Of the total shares of restricted stock granted, 20,000 shares vest 3 months from the grant date, 30,374 shares vest 1 year from the grant date, 30,000 shares have a vesting period of 2 years, 202,497 shares have a vesting period of 4 years and 350,000 shares vest at the date of grant.  
Public offering [Member]                        
Equity (Textual)                        
Common stock issued, shares     4,444,444 1,827,123 1,670,000              
Common stock, par value         $ 0.001              
Exercise price     $ 6.50                  
Fair value assumptions, expected term     4 years                  
Price per share $ 1.25   $ 4.50 $ 7.50 $ 7.50              
Gross proceeds from public offering     $ 20,000,000 $ 13,700,000 $ 12,500,000              
Net proceeds from public offering     $ 18,500,000 12,600,000 11,500,000              
Number of common shares issued 8,000,000                      
Underwriting discount         $ 900,000              
Underwriting agreement description         Under the terms of the underwriting agreement, the Company also granted the underwriters a 30-day option to purchase up to an additional 250,000 shares of common stock to cover over-allotments, if any, at the offering price.              
Other offering expenses         $ 100,000              
Auditor fees         $ 100,000              
Proceeds from the exercise of options       $ 1,200,000                
Number of additional stock option granted       157,123                
Warrants issued to purchase common stock, shares     3,333,333                  
Fair value of warrants     $ 3,540,659                  
[1] The volatility was estimated using the historical volatilities of the Company's common stock traded in NYSE MKT market.
[2] Management determined the dividend yield to be 0% based upon its expectation that it will not pay dividends for the foreseeable future.
[3] The risk-free interest rate was determined by management using the Treasury Bill rate as of the respective measurement date.