Loan and Security Agreements (Details) | 1 Months Ended | 9 Months Ended | 12 Months Ended |
Feb. 28, 2015USD ($)$ / sharesshares | Dec. 31, 2012USD ($) | Sep. 30, 2015USD ($)installment | Dec. 31, 2014USD ($)installment |
Loan and Security Agreements | | | | |
Repayment of existing debt | | | $ 15,784,150 | |
Value of warrants | | | 1,184,228 | |
Loss on extinguishment of debt | | | 1,035,981 | |
Secured debt | Oxford Loan | | | | |
Loan and Security Agreements | | | | |
Loss on extinguishment of debt | | | $ 1,000,000 | |
Secured debt | Oxford Loan | | | | |
Loan and Security Agreements | | | | |
Amount borrowed | | $ 15,000,000 | | |
Repayment of existing debt | $ 15,500,000 | | | |
Fixed interest rate (as a percent) | | | | 9.20% |
Number of consecutive monthly principal installments | installment | | | | 30 |
Final payment | | | | $ 675,000 |
Secured debt | Hercules Loan | | | | |
Loan and Security Agreements | | | | |
Maximum borrowing capacity | 25,000,000 | | | |
Amount borrowed | 16,500,000 | | | |
Additional amount available | $ 8,500,000 | | | |
Number of consecutive monthly principal installments | installment | | | 30 | |
Final payment | | | $ 610,500 | |
Secured debt | Hercules Loan | Minimum | | | | |
Loan and Security Agreements | | | | |
Fixed interest rate (as a percent) | | | 9.00% | |
Secured debt | Hercules Loan | Hercules | | | | |
Loan and Security Agreements | | | | |
Number of warrants (in shares) | shares | 180,274 | | | |
Exercise price of warrants (in dollars per share) | $ / shares | $ 5.89 | | | |
Value of warrants | $ 1,200,000 | | | |
Secured debt | Hercules Loan | Equity financings | Hercules | Right to participate in future equity financings | Maximum | | | | |
Loan and Security Agreements | | | | |
Equity financings amount | $ 2,000,000 | | | |
Secured debt | LIBOR | Oxford Loan | | | | |
Loan and Security Agreements | | | | |
Variable rate basis | | | | three-month U.S. Libor rate |
Variable interest rate margin (as a percent) | | | | 8.73% |
Secured debt | LIBOR | Oxford Loan | Minimum | | | | |
Loan and Security Agreements | | | | |
Variable rate base (as a percent) | | | | 0.47% |
Secured debt | Prime | Hercules Loan | | | | |
Loan and Security Agreements | | | | |
Variable rate basis | | | Prime minus 4.25% | |
Variable interest rate margin (as a percent) | | | 9.00% | |
Variable rate adjustment (as a percent) | | | 4.25% | |
Secured debt | First year | Hercules Loan | | | | |
Loan and Security Agreements | | | | |
Prepayment premium as percentage of outstanding principal | | | 3.00% | |
Secured debt | Second year | Hercules Loan | | | | |
Loan and Security Agreements | | | | |
Prepayment premium as percentage of outstanding principal | | | 2.00% | |
Secured debt | After the second year | Hercules Loan | | | | |
Loan and Security Agreements | | | | |
Prepayment premium as percentage of outstanding principal | | | 1.00% | |