v3.26.1
CASH, CASH EQUIVALENTS AND INVESTMENTS - Available-for-Sale Securities (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jul. 31, 2026
Jul. 31, 2025
Jul. 31, 2026
Jul. 31, 2025
Jan. 31, 2026
Cash and Cash Equivalents          
Interest receivable $ 4,000   $ 4,000   $ 3,400
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Current, Statement of Financial Position [Extensible Enumeration] Investments   Investments   Investments
Proceeds from sale of debt securities, available-for-sale $ 0 $ 0 $ 0 $ 0  
Amounts of gains or losses reclassified out of other comprehensive income 0 $ 0 0 $ 0  
Available-for-sale securities          
Amortized Cost 486,856   486,856   $ 400,573
Gross Unrealized Gains 223   223   3,501
Gross Unrealized Losses 6,522   6,522   475
Estimated Fair Value 480,557   480,557   403,599
US Treasury notes          
Available-for-sale securities          
Amortized Cost, Due within one year 30,371   30,371   45,446
Amortized Cost, Due in one to three years 163,051   163,051   77,931
Amortized Cost, Due in three to five years 293,434   293,434   277,196
Gross Unrealized Gains, Due within one year 105   105   127
Gross Unrealized Gains, Due in one to three years 118   118   1,182
Gross Unrealized Gains, Due in three to five years         2,192
Gross Unrealized Losses, Due within one year         8
Gross Unrealized Losses, Due in one to three years 555   555   13
Gross Unrealized Losses, Due in three to five years 5,967   5,967   454
Estimated Fair Value, Due within one year 30,476   30,476   45,565
Estimated Fair Value, Due in one to three years 162,614   162,614   79,100
Estimated Fair Value, Due in three to five years $ 287,467   $ 287,467   $ 278,934