Basic and Diluted Earnings Per Share (Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2022	Nov. 30, 2021	Nov. 30, 2022	Nov. 30, 2021
Basic earnings per share:
Net income	$ 360.3	$ 332.1	$ 739.5	$ 665.7
Weighted-average common shares outstanding	360.5	360.7	360.2	360.4
Basic earnings per share	$ 1.00	$ 0.92	$ 2.05	$ 1.85
Diluted earnings per share:
Net income	$ 360.3	$ 332.1	$ 739.5	$ 665.7
Weighted-average common shares outstanding	360.5	360.7	360.2	360.4
Dilutive effect of common share equivalents	1.8	2.4	2.1	2.5
Weighted-average common shares outstanding, assuming dilution	362.3	363.1	362.3	362.9
Diluted earnings per share	$ 0.99	$ 0.91	$ 2.04	$ 1.83
Weighted-average anti-dilutive common share equivalents	0.9	0.4	0.7	0.3