Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Jan. 31, 2023	Jan. 31, 2022
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income	$ 208.5	$ 191.1	$ 109.8	$ 69.7	$ 206.0	$ 153.9	$ 509.4	$ 429.6
Weighted-average common shares outstanding (in shares)	106.5						106.4
Weighted-average common shares outstanding – assuming dilution (in shares)	107.0						106.9
Net income per common share (in dollars per share)	$ 1.96			$ 0.64			$ 4.78	$ 3.96
Net Income - Assuming Dilution (in dollars per share)	$ 1.95			$ 0.64			$ 4.77	$ 3.96
Two-class method
Schedule of Earnings Per Share, Two Class Method [Line Items]
Net income	$ 208.5			$ 69.7			$ 509.4	$ 429.6
Less: Net income allocated to participating securities	0.2			0.1			0.7	1.2
Net income allocated to common stockholders	$ 208.3			$ 69.6			$ 508.7	$ 428.4
Weighted-average common shares outstanding (in shares)	106.5			108.1			106.4	108.1
Add: Dilutive effect of stock options (in shares)	0.1			0.1			0.1	0.0
Weighted-average common shares outstanding – assuming dilution (in shares)	106.6			108.2			106.5	108.1
Net income per common share (in dollars per share)	$ 1.96			$ 0.64			$ 4.78	$ 3.96
Net Income - Assuming Dilution (in dollars per share)	$ 1.95			$ 0.64			$ 4.78	$ 3.96