Investments (Details) - USD ($)	Jan. 31, 2026	Dec. 22, 2025	Apr. 30, 2025
Short-term investments:
Total short-term investments	$ 297,259,000
Long-term investments:
Total long-term investments	61,659,000		$ 31,627,000
Investments at cost		$ 3,000,000
U.S. government securities
Short-term investments:
Total short-term investments	175,071,000
Long-term investments:
Total long-term investments	14,086,000
Corporate securities
Short-term investments:
Total short-term investments	112,252,000
Equity securities and warrants
Long-term investments:
Total long-term investments	11,650,000		1,204,000
Investment in limited partnership funds
Long-term investments:
Equity method investments	35,923,000		30,423,000
Certificates of deposit
Short-term investments:
Total short-term investments	9,936,000
Available-for-sale securities
Long-term investments:
Total long-term investments	25,736,000		1,204,000
Equity method investments
Long-term investments:
Total long-term investments	$ 35,923,000		$ 30,423,000