Fair Values on Financial Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair value of financial assets and liabilities
Total financial assets	$ 117,358	$ 59,592
Money market funds
Fair value of financial assets and liabilities
Total financial assets	15,788	8,860
United States government agency securities
Fair value of financial assets and liabilities
Total financial assets	18,746	15,561
United States government agency securities | Short-term Investments
Fair value of financial assets and liabilities
Total financial assets	18,746	15,561
Corporate debt securities
Fair value of financial assets and liabilities
Total financial assets	82,824	35,171
Level 1
Fair value of financial assets and liabilities
Total financial assets	15,788	8,860
Level 1 | Money market funds
Fair value of financial assets and liabilities
Total financial assets	15,788	8,860
Level 2
Fair value of financial assets and liabilities
Total financial assets	101,570	50,732
Level 2 | United States government agency securities | Short-term Investments
Fair value of financial assets and liabilities
Total financial assets	18,746	15,561
Level 2 | Corporate debt securities
Fair value of financial assets and liabilities
Total financial assets	$ 82,824	$ 35,171