Condensed Consolidated Statements of Changes in Common Stockholders' Investment (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Statement Of Stockholders Equity [Abstract]
Cash dividends declared, per share	$ 1.50	$ 1.30
Other comprehensive income, tax benefit	$ 0	$ 3
Purchase of treasury stock	1,900,000	0.0
Employee incentive plans and other, shares issued	600,000	1,000,000.0