Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 730,543	$ 44,120
Issuance of warrants	741,828
Change in convertible preferred stock warrant valuation	239,683	56,322
Ending balance		401,949
Series E Convertible Preferred Stock Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Issuance of warrants		2,191,507
Exercise of warrants	(4,116)	$ (1,890,000)
Series D Convertible Preferred Stock Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Exercise of warrants	(91,798)
Convertible Note Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Reclassification of warrants	(1,386,035)
Series C-2 Convertible Preferred Stock Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Reclassification of warrants	(555)
Growth Term Loan
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Reclassification of warrants	$ (229,550)