FAIR VALUE MEASUREMENTS - Financial Instruments on a Recurring Basis (Details) - USD ($) $ in Thousands	Apr. 30, 2026	Jan. 31, 2026
Fair value of assets and liabilities measured on recurring and nonrecurring basis
Available-for-sale securities	$ 444,905	$ 403,599
Level 1 Inputs | Fair value, recurring
Fair value of assets and liabilities measured on recurring and nonrecurring basis
Totals	150,939	149,597
Level 1 Inputs | Fair value, recurring | Money market funds
Fair value of assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	150,939	149,597
Level 2 Inputs | Fair value, recurring
Fair value of assets and liabilities measured on recurring and nonrecurring basis
Totals	444,905	403,599
Level 2 Inputs | Fair value, recurring | U.S. Treasury notes
Fair value of assets and liabilities measured on recurring and nonrecurring basis
Available-for-sale securities	$ 444,905	$ 403,599