Consolidated Statements of Earnings - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Nov. 30, 2025	Aug. 31, 2025	Nov. 30, 2024	Aug. 31, 2024	Nov. 30, 2025	Nov. 30, 2024	May 31, 2025
Income Statement [Abstract]
Net sales	$ 871.9		$ 739.0		$ 1,744.8	$ 1,573.0
Cost of goods sold	778.7		659.0		1,536.4	1,392.6
Gross margin	93.2		80.0		208.4	180.4
Selling, general and administrative expense	70.9		61.1		138.8	118.1
Impairment of assets	0.6		0.0		0.6	0.0
Restructuring and other (income), net	0.0		0.0		(1.0)	0.0
Operating income	21.7		18.9		70.0	62.3
Other income (expense):
Miscellaneous income (expense), net	(0.1)		3.8		0.1	(2.1)
Interest expense, net	(2.7)		(2.1)		(5.6)	(4.7)
Equity in net income (loss) of unconsolidated affiliate	6.8		(0.9)		13.2	0.4
Earnings before income taxes	25.7		19.7		77.7	55.9
Income tax expense	4.2		3.6		17.6	7.6
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	$ 18.8		$ 12.8		$ 55.6	$ 41.2
Basic
Weighted average common shares outstanding	49,800,000		49,500,000		49,700,000	49,400,000
Earnings per share attributable to controlling interest	$ 0.38		$ 0.26		$ 1.12	$ 0.83
Diluted
Weighted average common shares outstanding	50,700,000		50,600,000		50,600,000	50,500,000
Earnings per share attributable to controlling interest	$ 0.37		$ 0.25		$ 1.1	$ 0.82
Common shares outstanding at end of period	49,857,111		49,500,000		49,857,111	49,500,000	49,548,895
Cash dividends declared per share	$ 0.16	$ 0.16	$ 0.16	$ 0.16	$ 0.32	$ 0.32