Net Loss Per Ordinary Share - Computation of Basic and Diluted Loss Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2020	Jul. 31, 2019
Numerator:
Net loss	$ (14,756)	$ (15,463)	$ (10,191)	$ (17,311)	$ (30,219)	$ (27,502)
Denominator:
Weighted-average ordinary shares - basic	34,480,307		32,860,974		34,280,318	32,676,509
Weighted-average ordinary shares - diluted	34,480,307		32,860,974		34,280,318	32,676,509
Net loss per ordinary share:
Basic	$ (0.43)		$ (0.31)		$ (0.88)	$ (0.84)
Diluted	$ (0.43)		$ (0.31)		$ (0.88)	$ (0.84)