Business Segment Information - Sales by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024	May 31, 2023
Business Segment Information
Net sales	$ 2,780.5	$ 2,318.9	$ 1,990.5
Cost of sales	2,252.8	1,876.6	1,620.4
Selling, general and administrative	347.7	312.2	230.4
Operating income	185.2	129.2	133.9
Inter-segment Sales
Business Segment Information
Net sales	112.2	97.3	99.3
Total Sales
Business Segment Information
Net sales	2,892.7	2,416.2	2,089.8
Operating income	284.5	189.7	167.2
Parts Supply
Business Segment Information
Net sales	1,099.6	967.0	818.4
Cost of sales	868.8	758.4	644.3
Selling, general and administrative	76.2	98.3	79.9
Other segment items	(2.2)	0.5	0.5
Operating income	156.8	109.8	93.7
Parts Supply | Inter-segment Sales
Business Segment Information
Net sales	19.8	8.6	19.3
Parts Supply | Total Sales
Business Segment Information
Net sales	1,119.4	975.6	837.7
Operating income	156.8	109.8	93.7
Repair & Engineering
Business Segment Information
Net sales	884.9	640.1	533.4
Cost of sales	705.8	520.1	438.1
Selling, general and administrative	101.0	68.2	58.8
Other segment items	(3.1)	(0.7)	1.2
Operating income	81.2	52.5	35.3
Repair & Engineering | Inter-segment Sales
Business Segment Information
Net sales	90.3	87.8	79.8
Repair & Engineering | Total Sales
Business Segment Information
Net sales	975.2	727.9	613.2
Operating income	81.2	52.5	35.3
Integrated Solutions
Business Segment Information
Net sales	695.3	641.9	546.9
Cost of sales	592.0	540.2	461.2
Selling, general and administrative	66.4	77.8	55.2
Other segment items	0.5
Operating income	36.4	23.9	30.5
Integrated Solutions | Inter-segment Sales
Business Segment Information
Net sales	2.1	0.9	0.2
Integrated Solutions | Total Sales
Business Segment Information
Net sales	697.4	642.8	547.1
Operating income	36.4	23.9	30.5
Expeditionary Services
Business Segment Information
Net sales	100.7	69.9	91.8
Cost of sales	83.7	57.9	76.8
Selling, general and administrative	6.9	8.5	7.3
Operating income	10.1	3.5	7.7
Expeditionary Services | Total Sales
Business Segment Information
Net sales	100.7	69.9	91.8
Operating income	$ 10.1	$ 3.5	$ 7.7