Accumulated Other Comprehensive Loss - Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Details) - Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other retirement plans income	$ 2	$ 3
Provision for income taxes		(1)
Net income	$ 2	$ 2