FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Millions	Feb. 28, 2019	May 31, 2018
Assets [Abstract]
Derivative financial instruments	$ 0	$ 29
Total assets	31,759	52,478
Liabilities [Abstract]
Derivative financial instruments	206	158
Commercial Paper Debt Securities [Member]
Assets [Abstract]
Investments and cash and cash equivalents	348	1,647
Money Market Funds [Member]
Assets [Abstract]
Investments and cash and cash equivalents	6,050	6,500
Corporate Debt Securities and Other [Member]
Assets [Abstract]
Investments and cash and cash equivalents	25,361	44,302
Fair Value Measurements Using Input Types Level 1 [Member]
Assets [Abstract]
Derivative financial instruments	0	0
Total assets	6,050	6,723
Liabilities [Abstract]
Derivative financial instruments	0	0
Fair Value Measurements Using Input Types Level 1 [Member] \| Commercial Paper Debt Securities [Member]
Assets [Abstract]
Investments and cash and cash equivalents	0	0
Fair Value Measurements Using Input Types Level 1 [Member] \| Money Market Funds [Member]
Assets [Abstract]
Investments and cash and cash equivalents	6,050	6,500
Fair Value Measurements Using Input Types Level 1 [Member] \| Corporate Debt Securities and Other [Member]
Assets [Abstract]
Investments and cash and cash equivalents	0	223
Fair Value Measurements Using Input Types Level 2 [Member]
Assets [Abstract]
Derivative financial instruments	0	29
Total assets	25,709	45,755
Liabilities [Abstract]
Derivative financial instruments	206	158
Fair Value Measurements Using Input Types Level 2 [Member] \| Commercial Paper Debt Securities [Member]
Assets [Abstract]
Investments and cash and cash equivalents	348	1,647
Fair Value Measurements Using Input Types Level 2 [Member] \| Money Market Funds [Member]
Assets [Abstract]
Investments and cash and cash equivalents	0	0
Fair Value Measurements Using Input Types Level 2 [Member] \| Corporate Debt Securities and Other [Member]
Assets [Abstract]
Investments and cash and cash equivalents	$ 25,361	$ 44,079

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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