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, 2017	May 31, 2016	May 31, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ 120	$ 121	$ 115
Provision for income taxes	(44)	(45)	(43)
Net income	$ (76)	$ (76)	$ (72)