Income Taxes (Details) - USD ($) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
Apr. 30, 2018 |
Jan. 31, 2018 |
Apr. 30, 2017 |
|
| Income Taxes [Abstract] | |||
| US Tax Act Impact | $ 95,400 | $ 95,400 | |
| US Tax Act Impact - Transition Tax | 101,100 | ||
| Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | $ (5,700) | ||
| Effective Income Tax Rate Reconciliation, Percent | 21.00% | 31.10% | |
| Provision for income taxes | $ 8,958 | $ 13,831 | |
| Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount | $ (2,600) | ||