Fair Value Measurements and Marketable Securities - Summary of Financial Assets and Liabilities Measured at Fair Value Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Cash equivalents:
Total cash equivalents	$ 2,400	$ 3,000
Fair Value, Measurements, Recurring [Member]
Cash equivalents:
Total cash equivalents	61,985	26,751
Marketable securities:
Total marketable securities	24,478	52,315
Total cash equivalents and marketable securities	86,463	79,066
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Cash equivalents:
Total cash equivalents	61,985	26,751
Marketable securities:
Total marketable securities	24,478	52,315
Total cash equivalents and marketable securities	86,463	79,066
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Cash equivalents:
Total cash equivalents	61,985	26,751
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member] | Level 2 [Member]
Cash equivalents:
Total cash equivalents	61,985	26,751
Fair Value, Measurements, Recurring [Member] | U.S. Government Securities [Member]
Marketable securities:
Total marketable securities		16,797
Fair Value, Measurements, Recurring [Member] | U.S. Government Securities [Member] | Level 2 [Member]
Marketable securities:
Total marketable securities		16,797
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Marketable securities:
Total marketable securities	13,513	14,060
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member] | Level 2 [Member]
Marketable securities:
Total marketable securities	13,513	14,060
Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Marketable securities:
Total marketable securities	10,965	21,458
Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member] | Level 2 [Member]
Marketable securities:
Total marketable securities	$ 10,965	$ 21,458