Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME	$ 775	$ 700	$ 1,371	$ 1,415
OTHER COMPREHENSIVE INCOME (LOSS):
Foreign currency translation adjustments, net of tax of $7, $21, $18, and $16	(90)	(230)	19	(218)
Amortization of prior service credit, net of tax of $11, $11, $22, and $22	(19)	(19)	(38)	(38)
Other comprehensive income (loss)	(109)	(249)	(19)	(256)
COMPREHENSIVE INCOME	$ 666	$ 451	$ 1,352	$ 1,159