| Long term debt (Tables)
 | 6 Months Ended | 
| Jun. 30, 2015 | 
|---|
| Debt Disclosure [Abstract] |  | 
| Schedule of Debt | 
|  |  
|  |  |  |  |  |  |  |  |  |  
|   |   |   |   |   |  
|   |   | June 30, 2015 |   | December 31, 2014 |  
|   |   |   |   |   |  
| Term Loan Agreements |   | $ | 7,327,500 | 
 |   | $ | 7,475,000 | 
 |  
| Equipment Financing Agreement |   | 502,548 | 
 |   | — | 
 |  
|   |   | 7,830,048 | 
 |   | 7,475,000 | 
 |  
| Less: Current portion of Long Term Debt |   | 1,728,333 | 
 |   | 1,495,000 | 
 |  
| Long Term Debt, net of Current Portion |   | $ | 6,101,715 | 
 |   | $ | 5,980,000 | 
 |  
|   |   |   |   |   |  
| Future minimum loan payments: |   |   |   |   |  
| 2015 |   | $ | 847,500 | 
 |   |   |  
| 2016 |   | 1,795,000 | 
 |   |   |  
| 2017 |   | 1,828,333 | 
 |   |   |  
| 2018 |   | 1,630,881 | 
 |   |   |  
| 2019 |   | 1,628,334 | 
 |   |   |  
| Thereafter |   | 100,000 | 
 |   |   |  
| Total |   | $ | 7,830,048 | 
 |   |   |  | 
| Schedule of Maturities of Long-term Debt | 
|  |  
|  |  |  |  |  |  |  |  |  |  
|   |   |   |   |   |  
|   |   | June 30, 2015 |   | December 31, 2014 |  
|   |   |   |   |   |  
| Term Loan Agreements |   | $ | 7,327,500 | 
 |   | $ | 7,475,000 | 
 |  
| Equipment Financing Agreement |   | 502,548 | 
 |   | — | 
 |  
|   |   | 7,830,048 | 
 |   | 7,475,000 | 
 |  
| Less: Current portion of Long Term Debt |   | 1,728,333 | 
 |   | 1,495,000 | 
 |  
| Long Term Debt, net of Current Portion |   | $ | 6,101,715 | 
 |   | $ | 5,980,000 | 
 |  
|   |   |   |   |   |  
| Future minimum loan payments: |   |   |   |   |  
| 2015 |   | $ | 847,500 | 
 |   |   |  
| 2016 |   | 1,795,000 | 
 |   |   |  
| 2017 |   | 1,828,333 | 
 |   |   |  
| 2018 |   | 1,630,881 | 
 |   |   |  
| 2019 |   | 1,628,334 | 
 |   |   |  
| Thereafter |   | 100,000 | 
 |   |   |  
| Total |   | $ | 7,830,048 | 
 |   |   |  |