Fair Value Measurement - Roll Forward for Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Add fair value of warrants issued	$ 5,666,935
Less repayments of principal	(1,064,177)	$ (1,681,664)
Less change in fair value of warrants	278,228	$ (347,330)
Warrant Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2015	770,964
Add fair value of warrants issued	5,666,935
Less change in fair value of warrants	(278,228)
Balance at March 31, 2016	6,159,671
Loan Payable Net of Discounts [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2015	10,334,029
Add amortization of discount	5,107
Less repayments of principal	(1,064,177)
Current portion	358,318
Non-current portion	8,916,641
Balance at March 31, 2016	$ 9,274,959