Summary of Available-for-Sale Securities (Detail) - USD ($)	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 83,007,000	$ 87,919,000
Gross Unrealized Gain	10,000	106,000
Gross Unrealized Loss	(1,645,000)	(255,000)
Allowance for Credit Loss	0	0	$ 0
Fair Value	81,372,000	87,770,000
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,187,000	7,170,000
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Allowance for Credit Loss	0	0
Fair Value	11,187,000	7,170,000
United States government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,757,000	25,761,000
Gross Unrealized Gain	0	1,000
Gross Unrealized Loss	(506,000)	(77,000)
Allowance for Credit Loss	0	0
Fair Value	20,251,000	25,685,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	48,574,000	52,611,000
Gross Unrealized Gain	8,000	105,000
Gross Unrealized Loss	(1,039,000)	(156,000)
Allowance for Credit Loss	0	0
Fair Value	47,543,000	52,560,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,489,000	2,377,000
Gross Unrealized Gain	2,000	0
Gross Unrealized Loss	(100,000)	(22,000)
Allowance for Credit Loss	0	0
Fair Value	$ 2,391,000	$ 2,355,000