Business Segment Information - Significant expenses for each segment (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2025	Aug. 31, 2024
Business Segment Information
Sales	$ 739.6	$ 661.7
Cost of Sales	605.9	544.5
Selling, General and Administrative	71.2	75.9
Operating Income	64.9	43.4
Gains (Losses) related to sale and exit of businesses, net	0.7	(0.1)
Other income (expense), net	(0.1)	(0.1)
Interest expense	(18.8)	(18.8)
Interest income	0.3	0.5
Income from continuing operations before income taxes	47.0	24.9
Inter-segment Sales
Business Segment Information
Sales	25.6	25.4
Operating segment
Business Segment Information
Sales	765.2	687.1
Reportable segment, aggregation before corporate and other operating segment
Business Segment Information
Sales	739.6	661.7
Cost of Sales	605.4	544.5
Selling, General and Administrative	63.1	62.1
Other Segment Items	(2.9)	(2.1)
Operating Income	74.0	57.2
Parts Supply
Business Segment Information
Sales	317.8	249.7
Cost of Sales	256.5	199.7
Selling, General and Administrative	23.3	20.3
Other Segment Items	(2.9)	(0.4)
Operating Income	40.9	30.1
Parts Supply | Inter-segment Sales
Business Segment Information
Sales	2.1	2.5
Parts Supply | Operating segment
Business Segment Information
Sales	319.9	252.2
Repair & Engineering
Business Segment Information
Sales	214.6	217.6
Cost of Sales	172.0	175.0
Selling, General and Administrative	22.0	23.1
Other Segment Items	0.2	(1.6)
Operating Income	20.4	21.1
Repair & Engineering | Inter-segment Sales
Business Segment Information
Sales	22.0	22.6
Repair & Engineering | Operating segment
Business Segment Information
Sales	236.6	240.2
Integrated Solutions
Business Segment Information
Sales	185.0	168.9
Cost of Sales	159.3	144.1
Selling, General and Administrative	16.2	17.2
Other Segment Items	(0.2)	(0.1)
Operating Income	9.7	7.7
Integrated Solutions | Inter-segment Sales
Business Segment Information
Sales	1.5	0.3
Integrated Solutions | Operating segment
Business Segment Information
Sales	186.5	169.2
Expeditionary Services
Business Segment Information
Sales	22.2	25.5
Cost of Sales	17.6	25.7
Selling, General and Administrative	1.6	1.5
Operating Income	3.0	(1.7)
Expeditionary Services | Operating segment
Business Segment Information
Sales	22.2	25.5
Corporate and other
Business Segment Information
Operating Income	$ (9.1)
Corporate and other | Reconciling segments
Business Segment Information
Operating Income		$ (13.8)