Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
Aug. 31, 2018	Aug. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 19,416
Translation adjustments	(162)	$ 109
Ending balance	19,173
Foreign Currency Translation Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(759)	(685)
Translation adjustments	(162)	109
Ending balance	(921)	(576)
Retirement Plans Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	181	270
Reclassifications from AOCI	(23)	(19)
Ending balance	158	251
Accumulated Other Comprehensive (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Ending balance	$ (763)	$ (325)

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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