Warrants (Tables)

12 Months Ended

Dec. 31, 2018

Warrants and Rights Note Disclosure [Abstract]

Summary of Warrant Liability Measured at Fair Value on a Recurring Basis

The following table presents the Company’s warrant liability measured at fair value on a recurring basis as of December 31, 2018:

	December 31, 2018
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Liabilities:
Warrant liability	$	—	$	—	$	1,240	$	1,240
Total liabilities at fair value	$	—	$	—	$	1,240	$	1,240

Summary of Fair Value Assumptions for Common Stock Warrants

The inputs to the valuation model that approximates a Monte Carlo simulation model are presented below. 

	December 31, 2018			January 9, 2018
Estimated dividend yield	—			—
Expected volatility	77.74%-100%			75.66%-100%
Risk-free interest rate	2.46		%	2.21		%
Expected term (years)	3.02			4.00
Fair value per share of common stock underlying the warrant	$	0.83		$	3.48
Warrant exercise price	$	4.66		$	4.66

Summary of Change in Fair Value of Warrant Liability, Valued Using Significant Unobservable Level 3 Inputs

The following table summarizes the change in the fair value of the warrant liability, which is valued using significant unobservable Level 3 inputs, for the year ended December 31, 2018:

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Beginning Balance		Issuance		Revaluations Included In Earnings			Exercises		Expirations		Ending Balance
Warrant liability	$	—	$	17,806	$	(16,566	)	$	—	$	—	$	1,240