Property and Equipment, Net - Property and Equipment (Details) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 39,341	$ 28,477
Less: accumulated depreciation and amortization	(21,534)	(17,928)
Property and equipment, net	17,807	10,549
Furniture and equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	6,051	3,595
Software development costs
Property Plant And Equipment [Line Items]
Total property and equipment, gross	31,380	23,444
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	1,812	1,255
Construction in progress
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 98	$ 183