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, 2019	May 31, 2018	May 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ 120	$ 121	$ 120
Provision for income taxes	(28)	(36)	(44)
Net income	$ 92	$ 85	$ 76