Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of the Company's Effective Tax Rate to the Statutory Federal Income Tax Rate

A reconciliation of the Company’s effective tax rate to the statutory federal income tax rate is as follows:

	Years Ended December 31,
	2021			2020
Federal income tax at statutory federal rate		21.0	%		21.0	%
State taxes		4.9			6.4
Permanent differences		0.3			—
Stock-based compensation		0.1			—
Tax credits		0.1			(0.1	)
Recapture of tax credits		0.0			34.9
Other		1.3			(3.2	)
Change in valuation allowance		(27.8	)		(59.4	)
Total		(0.1	)%		(0.4	)%

Schedule of Temporary Differences That Give Rise to Significant Net Deferred Tax Assets

Temporary differences that give rise to significant net deferred tax assets as of December 31, 2021 and 2020 are as follows:

	December 31,
(in thousands)	2021			2020
Deferred tax assets
Net operating losses	$	62,619		$	61,905
Capitalized research and development expenses		282			423
Credit carryforwards		167,498			167,501
Deferred compensation		1,993			1,890
Election out of installment method		956			820
Accrued expenses		44			124
Other temporary differences		672			720
Installment sale tax basis		15,869			15,869
Total gross deferred tax assets		249,933			249,252
Valuation allowance		(249,933	)		(249,252	)

Schedule of Changes in the Valuation Allowance

The change in the valuation allowance against the deferred tax assets in the years ended December 31, 2021 and 2020 was as follows:

(in thousands)	Balance at Beginning of Period		Additions		Deductions		Balance at End of Period
December 31, 2020		247,468		1,784		—		249,252
December 31, 2021		249,252		681		—		249,933