Employee Benefit Plans - Schedule of change in fair value of plan assets (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021
Change in plan assets:
Fair value of plan assets at beginning of year	$ 40.8
Fair value of plan assets at end of year	30.4	$ 40.8
U.K.
Change in plan assets:
Fair value of plan assets at beginning of year	40.8	36.6
Actual return on plan assets	(6.2)	(0.8)
Employer contributions	1.6	1.1
Defined Benefit Plan, Plan Assets, Benefits Paid	1.1	1.5
Foreign currency translation	(4.7)	5.4
Fair value of plan assets at end of year	$ 30.4	$ 40.8