Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024	May 31, 2023
Employee benefit plans
Pension expense	$ 3.9	$ 3.7	$ 3.8
Benefit plan contribution excise tax rate upon withdrawal	20.00%
Benefit plan remaining surplus plan assets	$ 1.6
Change in projected benefit obligation:
Non-cash, after-tax pension settlement charge	16.1
Defined Benefit Pension Plans
Employee benefit plans
Pension expense	1.4	$ 1.3	$ 1.2
Merged U.S. Plan
Change in the fair value of plan assets:
Funded status at end of year	$ 26.7
Netherlands Plan
Employee benefit plans
Discount rate (as a percent)	3.70%	3.60%
Pension expenses for discount rate	3.60%	3.70%	2.80%
Benefit plan assumptions used expected long term rate of return	4.80%	4.80%	3.90%
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$ 52.7	$ 51.3
Service cost	0.2	0.2
Interest cost	1.9	1.9
Net actuarial loss (gain)	(1.1)	0.4
Benefits and administrative payments	(2.2)	(2.0)
Foreign currency translation adjustment	2.3	0.9
Projected benefit obligation at end of year	53.8	52.7	$ 51.3
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	51.4	50.2
Actual return on plan assets	1.7	2.2
Employer contributions	0.4
Benefits and administrative payments	(2.2)	(2.0)
Foreign currency translation adjustment	(2.3)	(1.0)
Fair value of plan assets at end of year	53.6	51.4	50.2
Funded status at end of year	(0.2)	(1.3)
Accumulated other comprehensive loss	6.8	6.8
Accumulated benefit obligation	51.8	50.6
Accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	51.8	50.6
Net Periodic Benefit Cost
Service cost	0.2	0.2	0.2
Interest cost	$ 1.9	1.9	1.5
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Expected return on plan assets	$ (2.5)	(2.4)	(2.1)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Recognized net actuarial loss	$ 0.1
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Total	$ (0.3)	$ (0.3)	$ (0.4)
Key weighted-average assumptions used in the measurement of the company's projected benefit obligations
Discount rate (as a percent)	3.70%	3.60%
Weighted-average assumptions used to determine net periodic pension expense
Discount rate: (as a percent)	3.60%	3.70%	2.80%