Consolidated Statements of Changes in Common Stockholders' Investment (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Statement Of Stockholders Equity [Abstract]
Other comprehensive loss, tax	$ (43)	$ (57)	$ (21)
Purchase of treasury stock	20,000.00	6,600,000	4,300,000
Cash dividends declared, per share	$ 2.60	$ 2.60	$ 2.00
Employee incentive plans and other, shares issued	1,000,000.0	1,300,000	3,100,000