Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Domestic and Foreign Components of Loss Before Provision for Income Tax

The domestic and foreign components of loss before provision for income tax are as follows (in thousands):

	Year Ended December 31,
	2021			2020			2019
Domestic	$	(115,088	)	$	(90,137	)	$	(89,860	)
Foreign		—			—			—
Total	$	(115,088	)	$	(90,137	)	$	(89,860	)

Schedule of Effective Tax Rate For Provision of Income Tax Differs to Federal Statutory Rate

The effective tax rate of the provision for income taxes differs from the federal statutory rate as follows:

	Year Ended December, 31
	2021			2020			2019
Federal statutory income tax rate		21.0	%		21.0	%		21.0	%
State income taxes, net of federal benefit		—			—			—
Federal and state tax credits, net of reserves		1.8			2.7			2.5
Stock-based compensation		(0.6	)		(0.7	)		(0.4	)
Other permanent differences		(0.3	)		(0.1	)		(0.1	)
Change in valuation allowance		(21.9	)		(22.9	)		(23.0	)
		0	%		0	%		0	%

Schedule of Components of Deferred Tax Assets and Liability

The components of the deferred tax assets and liability are as follows (in thousands):

	Year Ended December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	85,417		$	73,405
Tax credits, net of reserves		13,965			11,874
Accrued liabilities		678			948
Stock-based compensation		4,904			4,091
Operating lease liability		638			1,411
Fixed and intangible assets		10,765			277
Gross deferred tax assets		116,367			92,006
Valuation allowance		(115,847	)		(90,797	)
Total deferred tax assets		520			1,209
Deferred tax liability:
Operating lease right-of-use asset		(520	)		(1,209	)
Total deferred tax liability		(520	)		(1,209	)
Net deferred tax assets (liability)	$	—		$	—

Schedule of Companies Unrecognized Tax Benefits

As of December 31, 2021, the Company’s total unrecognized tax benefit was $8.4 million, of which none of the tax benefit, if recognized, would affect the effective income tax rate due to the valuation allowance that currently offsets deferred tax assets. A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2021, 2020, and 2019 is as follows (in thousands):

	Year Ended December 31,
	2021		2020			2019
Balance at beginning of year	$	7,272	$	5,993		$	4,964
Decreases related to prior year tax positions		—		(24	)		(6	)
Additions based on tax positions related to current year		1,129		1,303			1,035
Balance at end of year	$	8,401	$	7,272		$	5,993