Short-term Investments - Summary of Hierarchy for Assets Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
U.S. Government Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	$ 14,993
U.S. Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	1,000
Money market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	13,219	$ 61,134
Quoted Market Prices for Identical Assets (Level 1) [Member] | U.S. Government Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	14,993
Quoted Market Prices for Identical Assets (Level 1) [Member] | Money market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	13,219	$ 61,134
Other Observable Inputs (Level 2) [Member] | U.S. Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	$ 1,000