Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Accumulated Other Comprehensive Loss
Balance at beginning of the period	$ (44.6)	$ (40.9)	$ (32.0)
Other comprehensive income (loss) before reclassifications	10.3	(4.9)	(10.4)
Amounts reclassified from AOCL	16.0	1.2	1.5
Total other comprehensive income (loss), net of tax	26.3	(3.7)	(8.9)
Balance at end of the period	(18.3)	(44.6)	(40.9)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(2.0)	(2.1)	0.3
Other comprehensive income (loss) before reclassifications	5.9	0.1	(2.4)
Amounts reclassified from AOCL	0.0
Total other comprehensive income (loss), net of tax	5.9	0.1	(2.4)
Balance at end of the period	3.9	(2.0)	(2.1)
Pensions Plans
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(42.6)	(38.8)	(32.3)
Other comprehensive income (loss) before reclassifications	4.4	(5.0)	(8.0)
Amounts reclassified from AOCL	16.0	1.2	1.5
Total other comprehensive income (loss), net of tax	20.4	(3.8)	(6.5)
Balance at end of the period	$ (22.2)	$ (42.6)	$ (38.8)