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		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ 26	$ 30	$ 53	$ 60
Provision for income taxes	(6)	(7)	(12)	(14)
Net income	$ 20	$ 23	$ 41	$ 46