Selected Quarterly Financial Information (Unaudited) - Schedule of Selected Quarterly Financial Data (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 6,817	$ 6,476	$ 26,790	$ 25,973
General and administrative	3,813	974	9,900	4,031
Total operating expenses	10,630	7,450	36,690	30,004
Loss from operations	(10,630)	(7,450)	(36,690)	(30,004)
Total other income (expense)	(186)	53	(614)	1,071
Net loss	$ (10,816)	$ (7,397)	$ (37,304)	$ (28,933)