Revenue - Concentration Risk (Details) - Geographic Concentration Risk - Revenue, Net |
3 Months Ended | |
|---|---|---|
Apr. 30, 2019 |
Apr. 30, 2018 |
|
| United States | ||
| Concentration Risk [Line Items] | ||
| Concentration risk, percentage | 60.00% | 63.00% |
| United Kingdom | ||
| Concentration Risk [Line Items] | ||
| Concentration risk, percentage | 10.00% | 9.00% |