Accumulated Other Comprehensive Loss - Reclassification Out of Accumulated Other Comprehensive Loss (Details) - Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ 30	$ 30	$ 90	$ 90
Provision for income taxes	(7)	(7)	(21)	(29)
Net income	$ 23	$ 23	$ 69	$ 61