EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Computation of Basic and Diluted Earnings Per Share [Abstract]
Net income		$ 2,197	$ 2,502	$ 3,945	$ 4,685
Weighted average common shares outstanding		4,239	4,417	4,278	4,434
Dilutive effect of employee stock plans		77	88	86	93
Dilutive weighted average common shares outstanding		4,316	4,505	4,364	4,527
Basic earnings per share		$ 0.52	$ 0.57	$ 0.92	$ 1.06
Diluted earnings per share		$ 0.51	$ 0.56	$ 0.90	$ 1.04
Shares subject to anti-dilutive stock options and restricted stock-based awards excluded from calculation	[1]	65	44	61	35

[1] These weighted shares relate to anti-dilutive stock options and restricted stock-based awards as calculated using the treasury stock method and could be dilutive in the future.