Convertible Senior Notes - Interest Expense (Details) - Convertible Debt - Convertible Senior Notes Due 2023 $ in Thousands |
3 Months Ended |
|---|---|
|
Apr. 30, 2019
USD ($)
| |
| Debt Instrument [Line Items] | |
| Contractual interest expense | $ 710 |
| Amortization of debt discount | 484 |
| Amortization of transaction costs | 5,970 |
| Total | $ 7,164 |