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STOCK-BASED COMPENSATION - Summary of Assumptions Used to Estimate Fair Value of Stock Options Granted (Details) - Stock Options Plans
6 Months Ended
Jul. 31, 2017
Jul. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award    
Dividend yield 1.10% 1.96%
Expected volatility 36.01% 33.85%
Risk-free interest rate 1.57% 1.36%
Expected life (in years) 3 years 4 months 6 days 5 years 6 months