Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Accumulated Other Comprehensive Loss
Balance at beginning of the period	$ (18.3)	$ (44.6)	$ (40.9)
Other comprehensive income before reclassifications	(2.1)	10.3	(4.9)
Amounts reclassified from AOCL	0.8	16.0	1.2
Total other comprehensive income (loss), net of tax	(1.3)	26.3	(3.7)
Balance at end of the period	(19.6)	(18.3)	(44.6)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Balance at beginning of the period	3.9	(2.0)	(2.1)
Other comprehensive income before reclassifications	(6.7)	5.9	0.1
Amounts reclassified from AOCL	0.0
Total other comprehensive income (loss), net of tax	(6.7)	5.9	0.1
Balance at end of the period	(2.8)	3.9	(2.0)
Pension Plans
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(22.2)	(42.6)	(38.8)
Other comprehensive income before reclassifications	4.6	4.4	(5.0)
Amounts reclassified from AOCL	0.8	16.0	1.2
Total other comprehensive income (loss), net of tax	5.4	20.4	(3.8)
Balance at end of the period	$ (16.8)	$ (22.2)	$ (42.6)