Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share Attributable to Controlling Interest (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended			6 Months Ended
		Nov. 30, 2025	Nov. 30, 2024	Aug. 31, 2024	Nov. 30, 2025	Nov. 30, 2024
Numerator (basic & diluted):
Net earnings		$ 21.5	$ 16.1	$ 32.2	$ 60.1	$ 48.3
Net earnings attributable to noncontrolling interests		2.7	3.3		4.5	7.1
Net earnings attributable to controlling interest - income available to common shareholders		$ 18.8	$ 12.8		$ 55.6	$ 41.2
Denominator:
Basic earnings weighted average common shares		49.8	49.5		49.7	49.4
Effect of dilutive securities		0.9	1.1		0.9	1.1
Diluted earnings adjusted weighted average common shares		50.7	50.6		50.6	50.5
Basic earnings per common share attributable to controlling interest		$ 0.38	$ 0.26		$ 1.12	$ 0.83
Diluted earnings per common share attributable to controlling interest		$ 0.37	$ 0.25		$ 1.1	$ 0.82
Anti-dilutive non-qualified stock options and restricted common share awards	[1]	0.1	0.1		0.1	0.2

[1] These non-qualified stock options and restricted common share awards were excluded from the calculation of diluted earnings per common share because their inclusion would have been anti-dilutive.