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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Income (Loss) Attributable to Parent [Abstract]
Net loss	$ (26,282)	$ (15,810)	$ (49,851)	$ (36,675)
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Weighted-average ordinary shares outstanding (in shares)	39,911	39,872	39,910	39,868
Earnings Per Share, Basic and Diluted [Abstract]
Basic and diluted net loss per share (in dollars per share)	$ (0.66)	$ (0.40)	$ (1.25)	$ (0.92)