Annual report pursuant to Section 13 and 15(d)

Intangible assets other than goodwill - Schedule of Estimated Future Amortization Expense (Details)

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Intangible assets other than goodwill - Schedule of Estimated Future Amortization Expense (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]    
Intangible assets, net $ 2,896,458 $ 1,065,967
Contract Asset and Liability    
Finite-Lived Intangible Assets [Line Items]    
2018 695,378  
2019 612,757  
2020 567,314  
2021 581,318  
2022 554,245  
Thereafter 1,841,739  
Intangible assets, net 4,852,751  
Contract Asset and Liability | Contract related intangibles    
Finite-Lived Intangible Assets [Line Items]    
2018 880,776  
2019 781,505  
2020 729,905  
2021 730,478  
2022 696,328  
Thereafter 2,434,472  
Intangible assets, net 6,253,464  
Contract Asset and Liability | Non-contract related intangibles    
Finite-Lived Intangible Assets [Line Items]    
2018 185,398  
2019 168,748  
2020 162,591  
2021 149,160  
2022 142,083  
Thereafter 592,733  
Intangible assets, net $ 1,400,713