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. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Basic earnings per share:
Net income	$ 354.5	$ 324.6	$ 877.4	$ 804.0
Weighted-average common shares outstanding	358.5	359.2	358.5	359.1
Basic earnings per share	$ 0.99	$ 0.90	$ 2.45	$ 2.24
Diluted earnings per share:
Net income	$ 354.5	$ 324.6	$ 877.4	$ 804.0
Weighted-average common shares outstanding	358.5	359.2	358.5	359.1
Dilutive effect of common share equivalents	2.5	2.4	2.6	2.5
Weighted-average common shares outstanding, assuming dilution	361.0	361.6	361.1	361.6
Diluted earnings per share	$ 0.98	$ 0.90	$ 2.43	$ 2.22
Weighted-average anti-dilutive common share equivalents	0.6	0.6	0.5	0.5