Funds Held for Clients and Corporate Investments (Realized Gains and Losses from Sale of Available-for-sale Securities) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
May 31, 2026 |
May 31, 2025 |
May 31, 2024 |
|
| Funds Held for Clients and Corporate Investments [Abstract] | |||
| Gross realized gains | $ 7.6 | $ 0.0 | $ 0.0 |
| Gross realized losses | 0.0 | (0.4) | (2.6) |
| Net realized (losses)/gains | $ 7.6 | $ (0.4) | $ (2.6) |