Service Revenue (Summary of Changes in Deferred Costs to Obtain and Fulfill Contracts) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Feb. 29, 2024 |
Feb. 28, 2023 |
Feb. 29, 2024 |
Feb. 28, 2023 |
|
| Capitalized Contract Cost [Line Items] | ||||
| Amortization | $ 173.4 | $ 163.0 | ||
| Costs To Fulfill Contracts [Member] | ||||
| Capitalized Contract Cost [Line Items] | ||||
| Balance, beginning of period | $ 75.8 | $ 74.5 | 75.3 | 72.3 |
| Capitalization of costs | 7.5 | 8.3 | 21.2 | 23.4 |
| Amortization | (6.7) | (6.6) | (19.9) | (19.5) |
| Balance, end of period | 76.6 | 76.2 | 76.6 | 76.2 |
| Costs To Obtain Contracts [Member] | ||||
| Capitalized Contract Cost [Line Items] | ||||
| Balance, beginning of period | 605.0 | 562.6 | 597.5 | 550.2 |
| Capitalization of costs | 53.7 | 65.2 | 163.1 | 172.2 |
| Amortization | (51.6) | (48.9) | (153.5) | (143.5) |
| Balance, end of period | $ 607.1 | $ 578.9 | $ 607.1 | $ 578.9 |