Income Taxes - Income Tax Provision (Benefit) Differs from Computed Using Federal Statutory Rate Applied to Income before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Tax provision computed at the federal statutory rate	$ (33,210)	$ (35,980)
State tax, net of federal benefit	(11,050)	(5,142)
Research and development expense tax credits	(1,838)	(2,686)
Change in uncertain tax benefit reserve	0	(27)
Change in tax credit carryforwards	0	109
Officers compensation	1,988	2,497
Stock based compensation	1,234	1,619
Permanent items and other	(173)	(37)
Tax differential on foreign earnings	0	(1)
Change in tax rate	(6,671)	(1,091)
Change in prior year deferred taxes	(353)	(998)
Valuation allowance	50,077	41,677
Total income tax expense (benefit)	$ 4	$ (60)