Business Segment Information - Geographic Data (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Business Segment Information
Net sales	$ 1,990.5	$ 1,820.0	$ 1,652.3
Long-lived assets	735.2	566.7
United States
Business Segment Information
Long-lived assets	559.9	400.4
Europe/Africa
Business Segment Information
Long-lived assets	78.5	74.3
Other
Business Segment Information
Long-lived assets	96.8	92.0
Foreign countries
Business Segment Information
Net sales	$ 588.6	$ 484.5	$ 370.5
Foreign countries | Total sales | Geographic Concentration Risk [Member]
Business Segment Information
Percentage of total sales	29.60%	26.60%	22.40%
Aviation Services
Business Segment Information
Net sales	$ 1,898.7	$ 1,745.8	$ 1,553.7
Aviation Services | North America
Business Segment Information
Net sales	1,443.5	1,346.2	1,255.7
Aviation Services | Europe/Africa
Business Segment Information
Net sales	267.4	223.7	207.5
Aviation Services | Other
Business Segment Information
Net sales	187.8	175.9	90.5
Expeditionary Services
Business Segment Information
Net sales	91.8	74.2	98.6
Expeditionary Services | North America
Business Segment Information
Net sales	89.6	74.0	95.9
Expeditionary Services | Other
Business Segment Information
Net sales	$ 2.2	$ 0.2	$ 2.7