Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2021	May 31, 2020	May 31, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		$ 18,295	$ 17,757	$ 19,416
Translation adjustments		422	(254)	(195)
Ending Balance		24,168	18,295	17,757
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification to retained earnings due to the adoption of ASU 2018-02	[1]		51
Foreign Currency Translation Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(1,207)	(954)	(759)
Translation adjustments		422	(254)	(195)
Ending Balance		(785)	(1,207)	(954)
Foreign Currency Translation Loss [Member] | ASU 2018-02 [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification to retained earnings due to the adoption of ASU 2018-02			1
Retirement Plans Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		60	89	181
Prior service cost (credit) arising during period			3
Reclassifications from AOCI		(7)	(82)	(92)
Ending Balance		53	60	89
Retirement Plans Adjustments [Member] | ASU 2018-02 [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification to retained earnings due to the adoption of ASU 2018-02			50
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(1,147)	(865)	(578)
Ending Balance		$ (732)	(1,147)	$ (865)
Accumulated Other Comprehensive Loss [Member] | ASU 2018-02 [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification to retained earnings due to the adoption of ASU 2018-02	[1]		$ 51

[1] ^{Relates to the adoption of ASU 2018-02.}