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Stock-Based Compensation - Black-Scholes Option-Pricing Model to Determine Fair Value of Assumptions Used for Employee Stock Options Granted (Detail) - Employee Stock Option - Employee Stock Option
12 Months Ended
Dec. 31, 2020
$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Expected term (in years) 5 years 6 months
Risk-free interest rate 0.40%
Expected volatility 96.80%
Dividend yield 0.00%
Weighted-average grant date fair value $ 4.64