Property and Equipment, Net (Details) - USD ($)
$ in Thousands
3 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Jan. 31, 2019
Property, Plant and Equipment [Line Items]      
Gross property and equipment $ 13,499   $ 11,138
Accumulated depreciation and amortization (5,799)   (5,366)
Property and equipment, net 7,700   5,772
Depreciation and amortization 400 $ 400  
Leasehold improvements      
Property, Plant and Equipment [Line Items]      
Gross property and equipment 7,719   6,512
Computers and equipment      
Property, Plant and Equipment [Line Items]      
Gross property and equipment 3,589   2,998
Capitalized internal-use software      
Property, Plant and Equipment [Line Items]      
Gross property and equipment 389   389
Furniture and fixtures      
Property, Plant and Equipment [Line Items]      
Gross property and equipment 1,802   1,239
Construction-in-progress      
Property, Plant and Equipment [Line Items]      
Gross property and equipment $ 1,400   $ 200