Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summarizes the Conclusions Reached Regarding Fair Value Measurements

The following table summarizes the conclusions reached regarding fair value measurements as of December 31, 2018, 2017 and 2016 (in thousands):

	Balance at December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Warrant liability, related party (1)	$	2,436	$	—	$	—	$	2,436
Total	$	2,436	$	—	$	—	$	2,436

	Balance at December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Warrant liability, related party (2)	$	492	$	—	$	—	$	492
Total	$	492	$	—	$	—	$	492

(1) Fair value determined using the Black-Scholes option pricing model. Expected volatility is based on a portfolio of selected stocks of companies believed to have market and economic characteristics similar to its own.  The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of valuation.

(2) Fair value determined using an option pricing model based on the Company’s current capitalization.  Expected volatility is based on a portfolio of selected stocks of companies believed to have market and economic characteristics similar to its own.  The risk-free rate is based on the yield of U.S. government securities with the same term as the option as of the valuation date.

	Changes in Level 3 Instruments for the years ended December 31, 2018, 2017 and 2016
	Balance at January 1		Net Change in fair value included in earnings		Purchases / Issuance		Sales / Repurchases			Balance at December 31,
2018
Warrant liability, related party	$	492	$	638	$	1,306	$	—		$	2,436
Total	$	492	$	638	$	1,306	$	—		$	2,436
2017
Warrant liability	$	167	$	—	$	—	$	(167	)	$	—
Warrant liability, related party		—		190		302		—			492
Total	$	167	$	190	$	302	$	(167	)	$	492
2016
Warrant liability	$	—	$	—	$	167	$	—		$	167
Total	$	—	$	—	$	167	$	—		$	167

Assumptions Used to Calculate Fair Value of Warrants

Significant inputs utilized in the valuation of the Letter Agreement Warrants were:

	December 31, 2018	December 31, 2017
Expected volatility	108.53% - 115.04%	90.00%
Risk-free interest rate	2.59% - 2.69%	2.40%