Net Loss Per Ordinary Share - Calculation of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net Income (Loss) Attributable to Parent [Abstract]
Net loss	$ (30,577)	$ (19,448)	$ (80,428)	$ (56,123)
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Weighted-average ordinary shares outstanding (in shares)	39,917	39,897	39,912	39,877
Earnings Per Share, Basic and Diluted [Abstract]
Basic and diluted net loss per share (in dollars per share)	$ (0.77)	$ (0.49)	$ (2.02)	$ (1.41)