Summary of Significant Accounting Policies - Goodwill (Details) $ in Millions	12 Months Ended
	May 31, 2024 USD ($)	May 31, 2023 USD ($) item
Goodwill
Goodwill, beginning balance	$ 175.8
Foreign currency translation adjustments	0.5
Goodwill, ending balance	554.8	$ 175.8
Number of reporting units | item		3
Expeditionary Services
Goodwill
Goodwill, beginning balance	18.8
Goodwill, ending balance	$ 18.8	$ 18.8