Net Loss Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Loss Per Ordinary Share (Detail) - shares	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	2,244,323	1,946,685
Options to purchase ordinary shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	771,769	1,003,060
Restricted stock and restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	1,441,462	926,156
Employee stock purchase plan awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	31,092	17,469