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, 2018	Nov. 30, 2017	[1]	Nov. 30, 2018	Nov. 30, 2017	[1]
Basic earnings per share:
Net income	$ 235.8	$ 198.8	[2]	$ 479.4	$ 409.2	[2]
Weighted-average common shares outstanding	359.1	359.1	[2]	359.1	359.0	[2]
Basic earnings per share	$ 0.66	$ 0.55	[2]	$ 1.34	$ 1.14	[2]
Diluted earnings per share:
Dilutive effect of common share equivalents	2.4	2.3		2.4	2.4
Weighted-average common shares outstanding, assuming dilution	361.5	361.4	[2]	361.5	361.4	[2]
Diluted earnings per share	$ 0.65	$ 0.55	[2]	$ 1.33	$ 1.13	[2]
Weighted-average anti-dilutive common share equivalents	0.6	1.2		0.5	1.1

[1] Amounts have been adjusted to reflect the adoption of ASC Topic 606.

[2] Amounts have been adjusted to reflect the adoption of Accounting Standards Codification ("ASC") Topic 606, "Revenue from Contracts with Customers" ("ASC Topic 606").