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		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ 27	$ 30	$ 80	$ 90
Provision for income taxes	(7)	(7)	(19)	(21)
Net income	$ 20	$ 23	$ 61	$ 69