EARNINGS PER SHARE (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2014		Nov. 30, 2013		Nov. 30, 2014		Nov. 30, 2013
Computation of Basic and Diluted Earnings Per Share [Abstract]
Net income	$ 2,502		$ 2,553		$ 4,685		$ 4,744
Weighted average common shares outstanding	4,417		4,535		4,434		4,571
Dilutive effect of employee stock plans	88		65		93		66
Dilutive weighted average common shares outstanding	4,505		4,600		4,527		4,637
Basic earnings per share	$ 0.57		$ 0.56		$ 1.06		$ 1.04
Diluted earnings per share	$ 0.56		$ 0.56		$ 1.04		$ 1.02
Shares subject to anti-dilutive stock options and restricted stock-based awards excluded from calculation	44	[1]	182	[1]	35	[1]	297	[1]

[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.