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		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Basic earnings per share:
Net income	$ 350.5	$ 354.5	$ 834.5	$ 877.4
Weighted-average common shares outstanding	360.6	358.5	359.8	358.5
Basic earnings per share	$ 0.97	$ 0.99	$ 2.32	$ 2.45
Diluted earnings per share:
Net income	$ 350.5	$ 354.5	$ 834.5	$ 877.4
Weighted-average common shares outstanding	360.6	358.5	359.8	358.5
Dilutive effect of common share equivalents	2.2	2.5	2.2	2.6
Weighted-average common shares outstanding, assuming dilution	362.8	361.0	362.0	361.1
Diluted earnings per share	$ 0.97	$ 0.98	$ 2.31	$ 2.43
Weighted-average anti-dilutive common share equivalents		0.6	0.7	0.5