Accumulated Other Comprehensive Income - Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Details) - Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other retirement plans income (expense)	$ 10	$ 107	$ 120
Provision for income taxes	(3)	(25)	(28)
Net income	$ 7	$ 82	$ 92