Fair Values on Financial Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair value of financial assets and liabilities
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
Total financial assets	81,041,000	88,340,000
Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	81,041,000	87,770,000
Money market funds
Fair value of financial assets and liabilities
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
Total short-term investments	14,472,000	7,170,000
United States government agency securities
Fair value of financial assets and liabilities
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
United States government agency securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	26,423,000	25,685,000
Corporate debt securities
Fair value of financial assets and liabilities
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
Corporate debt securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	36,795,000	52,560,000
Mortgage-backed securities
Fair value of financial assets and liabilities
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
Mortgage-backed securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	3,351,000	2,355,000
Warrant | Other Assets
Fair value of financial assets and liabilities
Warrants		570,000
Level 1
Fair value of financial assets and liabilities
Total financial assets	14,472,000	7,170,000
Level 1 | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	14,472,000	7,170,000
Level 1 | Money market funds
Fair value of financial assets and liabilities
Total short-term investments	14,472,000	7,170,000
Level 2
Fair value of financial assets and liabilities
Total financial assets	66,569,000	80,600,000
Level 2 | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	66,569,000	80,600,000
Level 2 | United States government agency securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	26,423,000	25,685,000
Level 2 | Corporate debt securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	36,795,000	52,560,000
Level 2 | Mortgage-backed securities | Short-term Investments
Fair value of financial assets and liabilities
Total short-term investments	$ 3,351,000	2,355,000
Level 3
Fair value of financial assets and liabilities
Total financial assets		570,000
Level 3 | Warrant | Other Assets
Fair value of financial assets and liabilities
Warrants		$ 570,000