Summary of Significant Accounting Policies - Stock-based Compensation (Details) - USD ($)
$ in Thousands |
3 Months Ended |
Apr. 30, 2018 |
Apr. 30, 2017 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| Total stock awards granted (in shares) |
700,577
|
753,487
|
| Aggregate grant date fair value |
$ 15,511
|
$ 7,761
|
| Dividend yield |
0.00%
|
|
| Stock-based compensation expense |
$ 2,520
|
$ 1,583
|
| Minimum [Member] |
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| Vesting period |
3 years
|
|
| Maximum [Member] |
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| Vesting period |
4 years
|
|
| (RSUs) [Member] |
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| RSUs and PSUs (in shares) |
80,411
|
324,487
|
| (PSUs) [Member] |
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| RSUs and PSUs (in shares) |
0
|
429,000
|
| Stock Option [Member] |
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
| Stock Options (in shares) |
620,166
|
0
|
| Expected volatility rate |
68.00%
|
|
| Expected term |
6 years 6 months
|
|
| Risk free interest rate |
2.67%
|
|