CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Details) - Held-to-maturity Securities - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jul. 31, 2019	Jan. 31, 2019
Cash and Cash Equivalents
Maturity period	246 days	250 days
Accrued interest on held-to-maturity securities	$ 0.9	$ 1.2
Weighted average annual interest rates of CDs (as a percent)	2.70%	2.60%