Summary of Available-for-Sale Securities (Detail) - USD ($)	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 83,242,000	$ 87,919,000
Gross Unrealized Gain	12,000	106,000
Gross Unrealized Loss	(2,165,000)	(255,000)
Allowance for Credit Loss	0	0	$ 0
Fair Value	81,089,000	87,770,000
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,351,000	7,170,000
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Allowance for Credit Loss	0	0
Fair Value	6,351,000	7,170,000
United States government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,364,000	25,761,000
Gross Unrealized Gain	4,000	1,000
Gross Unrealized Loss	(618,000)	(77,000)
Allowance for Credit Loss	0	0
Fair Value	24,750,000	25,685,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	48,354,000	52,611,000
Gross Unrealized Gain	4,000	105,000
Gross Unrealized Loss	(1,372,000)	(156,000)
Allowance for Credit Loss	0	0
Fair Value	46,986,000	52,560,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,173,000	2,377,000
Gross Unrealized Gain	4,000	0
Gross Unrealized Loss	(175,000)	(22,000)
Allowance for Credit Loss	0	0
Fair Value	$ 3,002,000	$ 2,355,000