BACKGROUND AND ORGANIZATION - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ (26,743)	$ (27,532)
Net cash used in operations	(26,307)	$ (34,999)
Cash and cash equivalents	$ 182,019		$ 156,720