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, 2019	Feb. 28, 2018	[1]	Feb. 28, 2019		Feb. 28, 2018	[1]
Basic earnings per share:
Net income	$ 324.6	$ 367.2	[2]	$ 804.0	[3]	$ 776.4	[2],[3]
Weighted-average common shares outstanding	359.2	359.2	[2]	359.1		359.1	[2]
Basic earnings per share	$ 0.90	$ 1.02	[2]	$ 2.24		$ 2.16	[2]
Diluted earnings per share:
Dilutive effect of common share equivalents	2.4	2.8		2.5		2.5
Weighted-average common shares outstanding, assuming dilution	361.6	362.0	[2]	361.6		361.6	[2]
Diluted earnings per share	$ 0.90	$ 1.01	[2]	$ 2.22		$ 2.15	[2]
Weighted-average anti-dilutive common share equivalents	0.6			0.5		0.8

[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").

[3] Amounts have been adjusted to reflect the adoption of Accounting Standards Update ("ASU") No. 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force)."