Condensed Statements of Consolidated Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Shares	Additional Capital	Retained Income	Accumulated Other Comprehensive Income (Loss)
Balance at Apr. 30, 2024	$ 7,693.9	$ 26.5	$ 5,713.9	$ 2,188.1	$ (234.6)
Balance, shares at Apr. 30, 2024		106,194,281
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	185.0			185.0
Other comprehensive income (loss)	2.4				2.4
Comprehensive income (loss)	187.4
Purchase of treasury shares	(2.6)	$ 0.0	(3.2)	0.6
Purchase of treasury shares, shares		(22,748)
Stock plans	5.4	$ 0.1	4.5	0.8
Stock plans, shares		236,997
Cash dividends declared	(114.6)			(114.6)
Balance at Jul. 31, 2024	7,769.5	$ 26.6	5,715.2	2,259.9	(232.2)
Balance, shares at Jul. 31, 2024		106,408,530
Balance at Apr. 30, 2024	7,693.9	$ 26.5	5,713.9	2,188.1	(234.6)
Balance, shares at Apr. 30, 2024		106,194,281
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	160.5
Other comprehensive income (loss)	(4.4)
Comprehensive income (loss)	156.1
Balance at Oct. 31, 2024	7,633.1	$ 26.6	5,723.7	2,121.8	(239.0)
Balance, shares at Oct. 31, 2024		106,416,530
Balance at Jul. 31, 2024	7,769.5	$ 26.6	5,715.2	2,259.9	(232.2)
Balance, shares at Jul. 31, 2024		106,408,530
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(24.5)			(24.5)
Other comprehensive income (loss)	(6.8)				(6.8)
Comprehensive income (loss)	(31.3)
Purchase of treasury shares		$ 0.0	0.3	0.0
Purchase of treasury shares	0.3
Purchase of treasury shares, shares		(972)
Stock plans	8.2	$ 0.0	8.2
Stock plans, shares		8,972
Cash dividends declared	(113.6)			(113.6)
Balance at Oct. 31, 2024	7,633.1	$ 26.6	5,723.7	2,121.8	(239.0)
Balance, shares at Oct. 31, 2024		106,416,530
Balance at Apr. 30, 2025	$ 6,082.6	$ 26.6	5,738.7	501.8	(184.5)
Balance, shares at Apr. 30, 2025	106,400,000	106,425,081
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (43.9)			(43.9)
Other comprehensive income (loss)	2.0				2.0
Comprehensive income (loss)	(41.9)
Purchase of treasury shares	(4.6)	$ 0.0	(5.8)	1.2
Purchase of treasury shares, shares		(47,688)
Stock plans	6.5	$ 0.1	5.3	1.1
Stock plans, shares		309,721
Cash dividends declared	(116.7)			(116.7)
Balance at Jul. 31, 2025	5,925.9	$ 26.7	5,738.2	343.5	(182.5)
Balance, shares at Jul. 31, 2025		106,687,114
Balance at Apr. 30, 2025	$ 6,082.6	$ 26.6	5,738.7	501.8	(184.5)
Balance, shares at Apr. 30, 2025	106,400,000	106,425,081
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 197.4
Other comprehensive income (loss)	1.8
Comprehensive income (loss)	199.2
Balance at Oct. 31, 2025	$ 6,060.2	$ 26.7	5,748.0	468.2	(182.7)
Balance, shares at Oct. 31, 2025	106,700,000	106,695,169
Balance at Jul. 31, 2025	$ 5,925.9	$ 26.7	5,738.2	343.5	(182.5)
Balance, shares at Jul. 31, 2025		106,687,114
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	241.3			241.3
Other comprehensive income (loss)	(0.2)				(0.2)
Comprehensive income (loss)	241.1
Purchase of treasury shares	(0.4)	$ 0.0	(0.5)	0.1
Purchase of treasury shares, shares		(3,711)
Stock plans	10.3	$ 0.0	10.3
Stock plans, shares		11,766
Cash dividends declared	(116.7)			(116.7)
Balance at Oct. 31, 2025	$ 6,060.2	$ 26.7	$ 5,748.0	$ 468.2	$ (182.7)
Balance, shares at Oct. 31, 2025	106,700,000	106,695,169