Property and Equipment, Net - Property and Equipment (Details) - USD ($) $ in Thousands	Jan. 31, 2019	Jan. 31, 2018
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 28,477	$ 19,177
Less: accumulated depreciation and amortization	(17,928)	(13,991)
Property and equipment, net	10,549	5,186
Furniture and equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	3,595	1,897
Software development costs
Property Plant And Equipment [Line Items]
Total property and equipment, gross	23,444	16,574
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	1,255	557
Construction in progress
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 183	$ 149