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Income Taxes - Difference Between Expected Income Tax Benefit and Actual Income Tax Benefit (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Income Tax Disclosure [Abstract]    
Income tax benefit at statutory rate $ (12,268) $ (9,533)
State income taxes, net of federal benefit (2,890) (2,760)
Non-U.S. income tax rate differential 0 (8)
Change in fair value of derivative 0 0
Change in federal tax rate 0 0
Research and development tax credits (693) (403)
Permanent items 729 288
Changes in valuation allowance 15,748 13,068
Other, net (626) (652)
Income tax expense (benefit) $ 0 $ 0