Service Revenue (Summary of Changes in Deferred Costs to Obtain and Fulfill Contracts) (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Aug. 31, 2026 |
Aug. 31, 2025 |
|
| Capitalized Contract Cost [Line Items] | ||
| Amortization | $ 66.0 | $ 60.4 |
| Costs To Fulfill Contracts [Member] | ||
| Capitalized Contract Cost [Line Items] | ||
| Balance, beginning of period | 135.9 | 87.0 |
| Capitalization of costs | 21.9 | 19.6 |
| Amortization | (10.1) | (7.6) |
| Balance, end of period | 147.7 | 99.0 |
| Costs To Obtain Contracts [Member] | ||
| Capitalized Contract Cost [Line Items] | ||
| Balance, beginning of period | 653.4 | 609.0 |
| Capitalization of costs | 64.2 | 48.9 |
| Amortization | (55.9) | (52.8) |
| Balance, end of period | $ 661.7 | $ 605.1 |