EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015
Earnings Per Share [Abstract]
Net income		$ 2,032	$ 2,197	$ 3,864	$ 3,945
Weighted average common shares outstanding		4,104	4,239	4,112	4,278
Dilutive effect of employee stock plans		91	77	96	86
Dilutive weighted average common shares outstanding		4,195	4,316	4,208	4,364
Basic earnings per share		$ 0.50	$ 0.52	$ 0.94	$ 0.92
Diluted earnings per share		$ 0.48	$ 0.51	$ 0.92	$ 0.90
Shares subject to anti-dilutive restricted stock-based awards and stock options excluded from calculation	[1]	77	65	74	61

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