Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance under EIP and ESPP (Detail) - shares	Oct. 31, 2017	Jan. 31, 2017
EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	5,821,923	5,167,688
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	1,561,841	1,252,465