Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair value measurement inputs

At December 31, 2019	Series A Warrants	Series B Warrants
Fair market of common stock (per share)	$6.86	$6.86
Expected term (years)	2.3	7.3
Risk free rate	1.62%	1.83%
Volatility	127%	115%

At January 15, 2020	Series A Warrants	Series B Warrants
Fair market of common stock (per share)	$3.77	$3.77
Expected term (years)	2.3	7.3
Risk free rate	1.62%	1.83%
Volatility	127%	115%

Assets and liabilities measured at fair value on a recurring basis

s below present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2020 and December 31, 2019 and indicate the fair value hierarchy of the valuation techniques utilized to determine such fair value.

	Fair value measurements at December 31, 2020
	Quoted prices in active markets for  identical assets		Significant other observable inputs		Significant unobservable  inputs		Balance as of
Description	(Level 1)		(Level 2)		(Level 3)		December 31, 2020
Assets
Cash equivalents:
Money market funds	$	2,873	$	—	$	—	$	2,873
Short-term investments:
U.S. government and agency securities	—		6,279		—		6,279
Total assets	$	2,873	$	6,279	$	—	$	9,152

	Fair value measurements at December 31, 2019
	Quoted prices in active markets for  identical assets		Significant other observable inputs		Significant unobservable  inputs		Balance as of
Description	(Level 1)		(Level 2)		(Level 3)		December 31, 2019
Assets
Cash equivalents:
Money market funds	$	2,622	$	—	$	—	$	2,622
U.S. government and agency securities	—		1,750		—		1,750
Short-term investments:
U.S. government agency securities	—		5,700		—		5,700
Total assets	$	2,622	$	7,450	$	—	$	10,072
Liabilities
Warrant liability	$	—	$	—	$	14,977	$	14,977
Total liabilities	$	—	$	—	$	14,977	$	14,977

Reconciliation of beginning and ending balances for the Level 3 warrant liability

The following tables show a reconciliation of the beginning and ending balances for the Level 3 warrant liability for each of the years ending December 31, 2020 and December 31, 2019. The Company's warrant liability was initially recorded in connection with the Company's concurrent public and private securities offerings completed during the year ended December 31, 2019. See Note 9 for more detailed information.

	Year ended December 31,
	2020		2019
Warrant liability, beginning of year	$	14,977	$	—
Warrants issued and classified as Level 3	—		24,518
Recognized gain (loss) from mark-to-market adjustment at December 31, 2019 balance sheet date	—		(9,541)
Recognized gain (loss) from mark-to-market adjustment prior to reclassification of warrant liability to equity	957		—
Reclassification from warrant liability to equity	(15,934)		—
Warrant liability, end of year	$	—	$	14,977