CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Balance at May. 31, 2020	$ 45.3	$ 478.6	$ 706.0	$ (282.7)	$ (44.6)	$ 902.6
Increase (Decrease) in Stockholders' Equity
Net income			35.8			35.8
Cash dividends			(0.1)			(0.1)
Stock option activity		3.6		3.0		6.6
Restricted stock activity		(2.4)		5.6		3.2
Other comprehensive income (loss), net of tax					26.3	26.3
Balance at May. 31, 2021	45.3	479.8	741.7	(274.1)	(18.3)	974.4
Increase (Decrease) in Stockholders' Equity
Net income			78.7			78.7
Stock option activity		2.0		19.3		21.3
Restricted stock activity		(4.3)		8.1		3.8
Repurchase of shares				(42.4)		(42.4)
Other comprehensive income (loss), net of tax					(1.3)	(1.3)
Balance at May. 31, 2022	45.3	477.5	820.4	(289.1)	(19.6)	1,034.5
Increase (Decrease) in Stockholders' Equity
Net income			90.2			90.2
Stock option activity		0.3		19.2		19.5
Restricted stock activity		6.7		2.2		8.9
Repurchase of shares				(50.1)		(50.1)
Other comprehensive income (loss), net of tax					(3.9)	(3.9)
Balance at May. 31, 2023	$ 45.3	$ 484.5	$ 910.6	$ (317.8)	$ (23.5)	$ 1,099.1