Condensed Consolidated Statements of Changes in Common Stockholders' Investment (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Statement Of Stockholders Equity [Abstract]
Cash dividends declared, per share	$ 0.75	$ 0.65	$ 3.00	$ 2.60
Other comprehensive income, tax benefit/(expense)	$ (2)	$ (1)	$ 3	$ (4)
Purchase of treasury stock	6,100,000	0.0	8,900,000	0.0
Employee incentive plans and other, shares issued	300,000	300,000	1,100,000	3,700,000