Net loss per share - Schedule of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share, Basic and Diluted [Abstract]
Net loss	$ (33,297)	$ (14,051)	$ (74,123)	$ (34,080)
Weighted average common stock outstanding, basic and diluted	3,027,825	2,084,719	2,829,160	1,851,811
Net loss per share - basic and diluted	$ (11.00)	$ (6.74)	$ (26.20)	$ (18.40)