Summary of business and significant accounting policies - Property and Equipment (Details) |
12 Months Ended |
|---|---|
Jan. 31, 2020 | |
| Furniture and fixtures | |
| Property, Plant and Equipment [Line Items] | |
| Useful life of property, plant and equipment (in years) | 5 years |
| Minimum | Computer equipment | |
| Property, Plant and Equipment [Line Items] | |
| Useful life of property, plant and equipment (in years) | 3 years |
| Maximum | Computer equipment | |
| Property, Plant and Equipment [Line Items] | |
| Useful life of property, plant and equipment (in years) | 5 years |