Annual report pursuant to Section 13 and 15(d)

Commitments and contingencies - Operating Lease Obligations (Details)

v3.6.0.2
Commitments and contingencies - Operating Lease Obligations (Details)
 12 Months Ended
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Jan. 31, 2012
vehicle
Office space and warehouse facilities      
Operating Leased Assets [Line Items]      
Rent expense, gross $ 691,769 $ 637,588  
Rent expense, sublease rent offset 63,842 113,472  
Rent expense, net 627,927 524,116  
Future minimum payments receivable 31,353    
Vehicles      
Operating Leased Assets [Line Items]      
Rent expense, net $ 6,918 $ 7,547  
Operating leased assets, number of assets | vehicle     2