Warrants (Tables)

6 Months Ended

Jun. 30, 2017

Equity [Abstract]

Summary of Assumptions using Black- Scholes Option Pricing Model to estimate fair value

The fair value of the 2016 Placement Warrants of $6.7 million and $2.7 million at June 30, 2017 and December 31, 2016, respectively, was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions:

	June 30, 2017		December 31, 2016
2016 Placement Warrant:
Expected term (in years)		6.2		6.7
Expected volatility		65.8%		63.6%
Risk-free interest rate		2.0%		2.3%
Expected dividend yield		0.0%		0.0%

The fair value of the 2017 Placement Warrants of $8.4 million was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions:

	June 30, 2017
2017 Placement Warrant:
Expected term (in years)		6.6
Expected volatility		65.9%
Risk-free interest rate		2.0%
Expected dividend yield		0.0%