Service Revenue (Summary of Changes in Deferred Revenue Related to Material Rights Performance Obligations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2025	Feb. 29, 2024	Feb. 28, 2025	Feb. 29, 2024
Revenue from Contract with Customer [Abstract]
Balance, beginning of period	$ 74.0	$ 69.8	$ 74.9	$ 62.0
Deferral of revenue	11.5	12.4	29.1	36.3
Recognition of unearned revenue	(9.9)	(8.9)	(28.4)	(25.0)
Balance, end of period	$ 75.6	$ 73.3	$ 75.6	$ 73.3