Revenue, Deferred Revenue and Commissions - Summary of Impact of Adopting New Revenue Standard on Condensed Consolidated Statement of Balance Sheet (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Disaggregation Of Revenue [Line Items]
Accounts receivable, net	$ 3,547	$ 2,858
Other current assets	3,429	4,397
Other assets	1,161	336
Accrued expenses	16,192	14,777
Deferred revenue	14,629	15,556
Accumulated deficit	(94,908)	$ (90,931)
Effect of Change | Topic 606
Disaggregation Of Revenue [Line Items]
Accounts receivable, net	174
Other current assets	367
Other assets	(825)
Accrued expenses	(202)
Deferred revenue	638
Accumulated deficit	(720)
Balances Without Adoption of Topic 606 | Topic 606
Disaggregation Of Revenue [Line Items]
Accounts receivable, net	3,721
Other current assets	3,796
Other assets	336
Accrued expenses	15,990
Deferred revenue	15,267
Accumulated deficit	$ (95,628)