Business Segment Information - Reconciliation of segment operating income to income from continuing operations before provision for income taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2023	Aug. 31, 2022
Business Segment Information
Operating income	$ 25.3	$ 31.2
Pension settlement charge	(26.7)
Losses related to sale and exit of business	(0.7)
Other income, net		0.2
Interest expense	(5.8)	(1.1)
Interest income	0.4	0.1
Income (Loss) from continuing operations before provision for income taxes	(7.5)	30.4
Operating segments
Business Segment Information
Operating income	33.2	36.3
Operating segments | Parts Supply
Business Segment Information
Operating income	15.1	18.3
Operating segments | Repair & Engineering
Business Segment Information
Operating income	9.1	7.4
Operating segments | Integrated Solutions
Business Segment Information
Operating income	7.7	8.3
Operating segments | Expeditionary Services
Business Segment Information
Operating income	1.3	2.3
Corporate and other
Business Segment Information
Operating income	$ (7.9)	$ (5.1)