Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Schedule of Fair Value of Financial Assets Measured on Recurring Basis

The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis by level within the fair value hierarchy:

	December 31, 2021
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	102,526	$	—	$	—	$	102,526

	December 31, 2020
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	101,919	$	—	$	—	$	101,919

Summary of Fair Value of Financial Liabilities Assumptions

At November 13, 2019, upon the issuance of Series A and Series B warrants and when the securities issuance obligation arose, the Company estimated the fair values of the financial liabilities using the following assumptions:

	Series A Warrant			Series B Warrant			Warrant Issuance Obligation			Common Stock Issuance Obligation
Expected term (in years)		5.2			2.3			5.2		N/A
Expected volatility		43	%		88	%		43	%	N/A
Risk-free interest rate		1.70	%		1.64	%		1.70	%	N/A
Expected dividend yield	— %			— %			— %			N/A
Discount for lack of marketability		30	%		30	%		32	%		32	%

At December 31, 2019, the Company remeasured these liabilities to their fair values using the following assumptions:

	Series A Warrant			Series B Warrant			Warrant Issuance Obligation			Common Stock Issuance Obligation
Expected term (in years)		5.1			2.2			5.1		N/A
Expected volatility		43	%		88	%		43	%	N/A
Risk-free interest rate		1.69	%		1.59	%		1.70	%	N/A
Expected dividend yield	— %			— %			— %			N/A
Discount for lack of marketability		25	%		25	%		25	%		25	%

At January 22, 2020, Series A and Series B warrants were no longer considered to be derivative instruments. The Company remeasured the fair value of the warrant liabilities at the time of reclassification to equity using the following assumptions:

	Series A Warrant			Series B Warrant
Expected term (in years)		5.0			2.1
Expected volatility		43	%		88	%
Risk-free interest rate		1.57	%		1.53	%
Expected dividend yield		—	%		—	%

The fair value of the Series A and Series B warrants at the time of issuance in November 2019, at December 31, 2019 and at the time they ceased to be derivative instruments in January 2020 were estimated to be $25.0 million, $45.9 million and $62.1 million, respectively. The Company recorded a $16.2 million and $20.9 million non-cash expense relating to the change in fair value of warrant liabilities in other expense (income), net in the accompanying consolidated statement of operations for the years ended December 31, 2020 and 2019, respectively.

On September 8, 2021, the Company amended certain terms of Series A warrants and Series B warrants (see Note 8). The amendments did not result in changes to the fair value of these warrants.

At January 31, 2020, the securities issuance obligation was settled by the issuance of common stock and a common stock warrant. The fair value of its common stock issuance obligation was remeasured based on the value of the common stock at the time of issuance. The fair value of the warrant issuance obligation was remeasured using the following assumptions:

	Warrant Issuance Obligation
Expected term (in years)		5.0
Expected volatility		43	%
Risk-free interest rate		1.57	%
Expected dividend yield	— %

Summary of Changes in Fair Values Level Financial Liabilities Recurring Basis Using Unobservable Inputs

The following table provides a summary of changes in the estimated fair values of the Company’s Level 3 financial liabilities, which were measured at fair value on a recurring basis using unobservable inputs:

	Series A Warrant Liability			Series B Warrant Liability			Warrant Issuance Obligation			Common Stock Issuance Obligation			Total
	(in thousands)
Balance, December 31, 2019	$	32,616		$	13,319		$	3,036		$	7,449		$	56,420
Changes in fair value		11,597			4,643			152			1,333			17,725
Settlement of financial liabilities by    securities issuance		—			—			(3,188	)		(8,782	)		(11,970	)
Reclassification to equity		(44,213	)		(17,962	)		—			—			(62,175	)
Balance, December 31, 2020 and 2021	$	—		$	—		$	—		$	—		$	—