Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance			$ 16,073
Translation adjustments	$ (90)	$ (230)	19	$ (218)
Ending balance	17,055		17,055
Foreign Currency Translation Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(576)	(502)	(685)	(514)
Translation adjustments	(90)	(230)	19	(218)
Ending balance	(666)	(732)	(666)	(732)
Retirement Plans Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	251	326	270	345
Reclassifications from AOCI	(19)	(19)	(38)	(38)
Ending balance	232	307	232	307
Accumulated Other Comprehensive (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Ending balance	$ (434)	$ (425)	$ (434)	$ (425)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 20
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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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-Publisher FASB
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-SubTopic 10
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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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