Debt (Tables)

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Schedule of debt valuation assumptions

The assumptions used in the Black-Scholes option-pricing model remain unchanged and are determined as follows:

	March 31, 2020
Volatility	98.01	%
Risk-free interest rate	1.58	%
Expected life (in years)	7
Dividend yield	0 %

The assumptions used in the Black-Scholes option-pricing model are determined as follows:

	March 31, 2020		December 31, 2019
Volatility	98.04	%	98.04	%
Risk-free interest rate	0.55	%	1.81	%
Weighted average expected life (in years)	6.1		6.25
Dividend yield	—	%	—	%

Schedule of carrying amounts of debt

The net carrying amounts of the liability components consists of the following (in thousands):

	March 31, 2020		December 31, 2019
Principal	$	37,955	$	36,502
Less: debt discount	(4,705)		(4,905)
Net carrying amount	$	33,250	$	31,597

Schedule of interest expense recognized

The following table presents the interest expense recognized related to the 2024 Notes and 2022 Loan (in thousands):

	Three months ended March 31,
	2020		2019
Contractual interest expense	$	1,453	$	221
Accretion of debt discount	200		100
Total	$	1,653	$	321