Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid insurance	$ 991	$ 918
Prepaid research and development project costs	321	853
Other receivables	311	190
Other	792	408
Total prepaid expenses and other current assets	$ 2,415	$ 2,369