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
	Aug. 31, 2019	Aug. 31, 2018
Basic earnings per share:
Net income	$ 264.2	$ 243.6	[1]
Weighted-average common shares outstanding	358.6	359.1
Basic earnings per share	$ 0.74	$ 0.68
Diluted earnings per share:
Net income	$ 264.2	$ 243.6	[1]
Weighted-average common shares outstanding	358.6	359.1
Dilutive effect of common share equivalents	2.9	2.4
Weighted-average common shares outstanding, assuming dilution	361.5	361.5
Diluted earnings per share	$ 0.73	$ 0.67
Weighted-average anti-dilutive common share equivalents	0.3	0.3

[1] Amounts have been adjusted to reflect 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).”