Summary of Significant Accounting Policies - Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Risk-free interest rate, Minimum	0.50%	0.36%
Risk-free interest rate, Maximum	1.36%	1.68%
Expected volatility, Minimum	72.53%	71.11%
Expected volatility, Maximum	74.80%	74.41%
Maximum [Member]
Expected life in years	6 years 3 months	6 years 3 months
Minimum [Member]
Expected life in years	5 years 6 months	5 years 9 months