Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables summarizes the types of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	December 31, 2021
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	831	$	—	$	—	$	831
Commercial paper	—		2,000		—		2,000
Corporate bonds	—		4,410		—		4,410
Cash equivalents	831		6,410		—		7,241
U.S. Government agency bonds	14,977		5,504		—		20,481
Commercial paper	—		19,107		—		19,107
Corporate bonds	—		2,914		—		2,914
Marketable securities	14,977		27,525		—		42,502
Total financial assets	$	15,808	$	33,935	$	—	$	49,743

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	10,533	$	—	$	—	$	10,533
Cash equivalents	10,533		—		—		10,533
Total financial assets	$	10,533	$	—	$	—	$	10,533

Schedule of Unrealized Gains and Losses and Fair Value of Marketable Securities

The following table summarizes the cost, unrealized gains and losses and fair value of marketable securities (in thousands):

	December 31, 2021
	Amortized Cost		Unrealized Losses		Unrealized Gains		Fair Value
U.S. Government agency bonds	$	20,509	$	(28)	$	—	$	20,481
Corporate bonds	2,915		(1)		—		2,914
Commercial paper	19,102		—		5		19,107
Marketable securities	$	42,526	$	(29)	$	5	$	42,502
Amounts recognized on the consolidated balance sheet
Short-term marketable securities							31,561
Long-term marketable securities							10,941
Marketable securities							$	42,502

Schedule of Assumptions Used in Determining Fair Value

The fair value of the 2020 Notes derivative liability was determined using the following assumptions:

	April 17,
	2020
Risk-free interest rate	0.2		%
Current Series G-1 convertible preferred stock value per share	$	0.84
Series G-1 convertible preferred stock volatility	34.4		%

Schedule of Fair Value of Liabilities

The change in fair value of the derivative liabilities is summarized below (in thousands):

	Success Fee Derivative Liability		2020 Notes Derivative Liability
Beginning fair value, January 1, 2020	$	1,165	$	—
Fair value at inception	—		3,900
Change in fair value	710		(3,900)
Payment of Success Fee	(1,875)		—
Ending fair value, December 31, 2020	$	—	$	—