Marketable Securities - Summary of Cash, Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	$ 30,347	$ 22,493	$ 49,326
Cash and cash equivalents, Fair Value	30,347	22,493
Total cash, cash equivalents and marketable securities, Amortized Cost	37,103	56,258
Total cash, cash equivalents and marketable securities, Unrealized Gains	13	19
Total cash, cash equivalents and marketable securities, Unrealized Losses		(1)
Total cash, cash equivalents and marketable securities, Fair Value	37,116	56,276
U.S. treasuries [Member]
Schedule Of Available For Sale Securities [Line Items]
Marketable securities, Amortized Cost	6,756	33,765
Marketable securities, Unrealized Gains	13	19
Marketable securities, Unrealized Losses		(1)
Marketable securities, Fair Value	$ 6,769	$ 33,783