Funds Held for Clients and Corporate Investments (Realized Gains and Losses from Sale of Available-for-sale Securities) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Nov. 30, 2022 |
Nov. 30, 2021 |
Nov. 30, 2022 |
Nov. 30, 2021 |
|
| Funds Held for Clients and Corporate Investments [Abstract] | ||||
| Gross realized gains | $ 0.0 | $ 0.0 | $ 0.1 | $ 0.1 |
| Gross realized losses | (0.0) | (0.0) | (0.0) | (0.0) |
| Net realized gains | $ (0.0) | $ 0.0 | $ 0.1 | $ 0.1 |