Net Income (Loss) Per Ordinary Share - Computation of Basic and Diluted Net Income (Loss) Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Numerator:
Net income (loss)	$ (44,792)	$ (30,447)	$ 18,852
Denominator:
Weighted-average ordinary shares - basic	33,083,562	32,713,606	33,224,803
Effect of dilutive securities:
Employee stock options	0	0	961,797
Restricted stock and restricted stock units	0	0	390,145
Employee stock purchase plan	0	0	6,405
Weighted-average ordinary shares - diluted	33,083,562	32,713,606	34,583,150
Net income (loss) per ordinary share:
Basic	$ (1.35)	$ (0.93)	$ 0.57
Diluted	$ (1.35)	$ (0.93)	$ 0.55