Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Nov. 30, 2023	May 31, 2025		May 31, 2024		May 31, 2023
Numerator (basic & diluted):
Net earnings attributable to controlling interest - income available to common shareholders		$ 110.7		$ 154.7		$ 87.1
Denominator:
Denominator for basic earnings per common share attributable to controlling interest - weighted average common shares		49,500,000		49,300,000		49,300,000
Effect of dilutive securities		1,000,000		500,000		0
Denominator for diluted earnings per common share attributable to controlling interest - adjusted weighted average common shares		50,500,000		49,800,000		49,300,000
Basic earnings per common share attributable to controlling interest		$ 2.24		$ 3.14		$ 1.77
Diluted earnings per common share attributable to controlling interest		$ 2.19		$ 3.11		$ 1.77
Anti-dilutive non-qualified stock options and restricted common share awards	0	200,000	[1]	0	[1]	0	[1]

[1] These non-qualified stock options and restricted common share awards were excluded from the calculation of diluted earnings per share because their inclusion would have been anti-dilutive. There were no anti-dilutive non-qualified stock options and restricted common share awards prior to the Separation. The number of anti-dilutive non-qualified stock options and restricted common share awards for 2024 was less than 0.1 million.