Net loss per share - Summary of Calculation of Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net loss attributable to common shareholders:
Basic and diluted	$ (31,136)	$ (13,641)
Weighted-average common shares outstanding:
Basic and diluted (in shares)	48,686,718	32,020,437
Net loss per common share-basic and diluted (in dollars per share)	$ (0.64)	$ (0.43)