Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2022
Accumulated Other Comprehensive Loss
Beginning Balance	$ (23.5)	$ (19.6)	$ (18.3)
Other comprehensive income (loss) before reclassifications	(0.1)	(2.2)	(2.1)
Amounts reclassified from AOCL	14.8	(1.7)	0.8
Total other comprehensive income loss	14.7	(3.9)	(1.3)
Ending Balance	(8.8)	(23.5)	(19.6)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Beginning Balance	(5.7)	(2.8)	3.9
Other comprehensive income (loss) before reclassifications	0.2	(2.9)	(6.7)
Amounts reclassified from AOCL	0.0
Total other comprehensive income loss	0.2	(2.9)	(6.7)
Ending Balance	(5.5)	(5.7)	(2.8)
Pensions Plans
Accumulated Other Comprehensive Loss
Beginning Balance	(17.8)	(16.8)	(22.2)
Other comprehensive income (loss) before reclassifications	(0.3)	0.7	4.6
Amounts reclassified from AOCL	14.8	(1.7)	0.8
Total other comprehensive income loss	14.5	(1.0)	5.4
Ending Balance	$ (3.3)	$ (17.8)	$ (16.8)