Summary of Available-for-Sale Securities (Detail) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 83,828,000	$ 87,919,000
Gross Unrealized Gain	50,000	106,000
Gross Unrealized Loss	(2,837,000)	(255,000)
Allowance for Credit Loss	0	0	$ 0
Fair Value	81,041,000	87,770,000
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,472,000	7,170,000
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Allowance for Credit Loss	0	0
Fair Value	14,472,000	7,170,000
United States government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	27,200,000	25,761,000
Gross Unrealized Gain	41,000	1,000
Gross Unrealized Loss	(818,000)	(77,000)
Allowance for Credit Loss	0	0
Fair Value	26,423,000	25,685,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	38,496,000	52,611,000
Gross Unrealized Gain	2,000	105,000
Gross Unrealized Loss	(1,703,000)	(156,000)
Allowance for Credit Loss	0	0
Fair Value	36,795,000	52,560,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,660,000	2,377,000
Gross Unrealized Gain	7,000	0
Gross Unrealized Loss	(316,000)	(22,000)
Allowance for Credit Loss	0	0
Fair Value	$ 3,351,000	$ 2,355,000