Summary of significant accounting policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2020		Feb. 01, 2020	Jan. 31, 2020	[1]
Concentration Risk [Line Items]
Lease right-of-use assets	$ 3,192	[1]	$ 2,741	$ 0
Operating lease liabilities	$ 3,446		$ 2,928
Accounts Receivable | Customer Concentration Risk | Customer One
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%
Accounts Receivable | Customer Concentration Risk | Customer Two
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%

[1] Figures as of October 31, 2020 reflect the Company's February 1, 2020 adoption of Accounting Standards Codification No. 842, Leases (ASC 842). For additional details, see Note 3(c), "Summary of significant accounting policies — Impact of recently adopted accounting pronouncements."