FAIR VALUE MEASUREMENTS - CONTINGENT CONSIDERATION TABLE (Details) - USD ($)
$ in Thousands
3 Months Ended
Apr. 30, 2018
Apr. 30, 2017
Changes in the estimated fair value of liability for contingent consideration measured using significant unobservable inputs (Level 3)    
Payments of contingent consideration $ (3,100) $ (2,400)
Liability for contingent consideration    
Changes in the estimated fair value of liability for contingent consideration measured using significant unobservable inputs (Level 3)    
Fair value measurement at the beginning of the period 62,830 52,733
Contingent consideration liabilities recorded for business combinations, including measurement period adjustments 69 1,900
Changes in fair values, recorded in operating expenses (822) 3,479
Payments of contingent consideration (3,084) (2,363)
Fair value measurement at the end of the period $ 58,824 $ 55,749