Quarterly report pursuant to Section 13 or 15(d)

Stock options and warrants (Other common stock purchase options and warrants) (Narrative) (Details)

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Stock options and warrants (Other common stock purchase options and warrants) (Narrative) (Details) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2013
Stock options and warrants [Abstract]      
Shares issued for warrants exercised 1,161,570    
Value of shares issued for warrants exercised $ 1,580,000    
Exercise price of warrants 1.36   1.36
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expense 403,021 484,222  
Nonqualified [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Awards outstanding 3,460,935   4,622,505
Stock-based compensation expense 0 14,000  
Fair value of options vested 0 14,178  
Unrecognized compensation expense $ 0