CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Details) - Held-to-maturity Securities - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Apr. 30, 2020	Jan. 31, 2020
Cash and Cash Equivalents
Maturity period	187 days	165 days
Accrued interest on held-to-maturity securities	$ 0.6	$ 0.5
Weighted average annual interest rates of CDs (as a percent)	1.80%	1.80%