Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Oct. 31, 2025	Jul. 31, 2025	Oct. 31, 2024	Jul. 31, 2024	Oct. 31, 2025	Oct. 31, 2024
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income (loss)	$ 241.3	$ (43.9)	$ (24.5)	$ 185.0	$ 197.4	$ 160.5
Net income (loss) per common share (in dollars per share)	$ 2.26		$ (0.23)		$ 1.85	$ 1.51
Net income (loss) per common share – assuming dilution	$ 2.26		$ (0.23)		$ 1.85	$ 1.51
Two-class method
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income (loss)	$ 241.3		$ (24.5)		$ 197.4	$ 160.5
Less: Net income (loss) allocated to participating securities	0.0		0.0		0.0	0.0
Net income (loss) allocated to common stockholders	$ 241.3		$ (24.5)		$ 197.4	$ 160.5
Weighted-average common shares outstanding	106.7		106.4		106.6	106.4
Add: Dilutive effect of stock options (in shares)	0.0		0.0		0.0	0.0
Weighted-average common shares outstanding – assuming dilution (in shares)	106.7		106.4		106.6	106.4
Net income (loss) per common share (in dollars per share)	$ 2.26		$ (0.23)		$ 1.85	$ 1.51
Net income (loss) per common share – assuming dilution	$ 2.26		$ (0.23)		$ 1.85	$ 1.51