Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income (loss)	$ 744.0	$ (91.3)	$ 631.7
Net income (loss) per common share (in dollars per share)	$ 7.14	$ (0.86)	$ 5.84
Net income (loss) per common share - assuming dilution (in dollars per share)	$ 7.13	$ (0.86)	$ 5.83
Two-class method [Member]
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income (loss)	$ 744.0	$ (91.3)	$ 631.7
Less: Net income (loss) allocated to participating securities	0.2	(0.1)	1.8
Net income (loss) allocated to common stockholders	$ 743.8	$ (91.2)	$ 629.9
Weighted-average common shares outstanding (in shares)	104.1	106.2	107.9
Add: Dilutive effect of stock options (in shares)	0.1	0.0	0.0
Weighted-average common shares outstanding – assuming dilution (in shares)	104.2	106.2	107.9
Net income (loss) per common share (in dollars per share)	$ 7.14	$ (0.86)	$ 5.84
Net income (loss) per common share - assuming dilution (in dollars per share)	$ 7.14	$ (0.86)	$ 5.84