Consolidated Statements of Changes in Common Stockholders' Investment (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017
Statement Of Stockholders Equity [Abstract]
Other comprehensive loss, tax	$ (57)	$ (21)	$ (9)
Purchase of treasury stock	6,600,000	4,300,000	3,000,000
Cash dividends declared, per share	$ 2.60	$ 2.00	$ 1.60
Employee incentive plans and other, shares issued	1,300,000	3,100,000	3,500,000