Cash Equivalents and Short-Term Investments - Narrative (Details) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jul. 31, 2025 |
Jul. 31, 2024 |
Jul. 31, 2025 |
Jul. 31, 2024 |
|
| Cash and Cash Equivalents [Abstract] | ||||
| Interest and investment income | $ 11,500,000 | $ 12,800,000 | $ 22,400,000 | $ 24,900,000 |
| Net amortization of premiums or discounts on short-term investments | 2,600,000 | 4,200,000 | 5,605,000 | 9,141,000 |
| Accretion expense | $ 0 | $ 0 | $ 0 | $ 100,000 |