Supplemental information - schedule of redeemable non-controlling interest (Details) - USD ($) $ in Millions	12 Months Ended
Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 1,042	$ 319	$ 0
Recognition upon acquisition of subsidiary	0	2,684	309
Acquisitions of non-controlling interests	0	(2,047)	0
Net loss attributable to Redeemable non-controlling interests	(21)	(73)	(3)
Redemption price adjustments	442	179	19
Reclassifications to accrued expenses and other liabilities	(1,314)	0	0
Other	18	(20)	(6)
Ending balance	167	1,042	319
Conversion of Stock [Line Items]
Recognition upon acquisition of subsidiary	$ 0	2,684	$ 309
VillageMD
Increase (Decrease) in Temporary Equity [Roll Forward]
Recognition upon acquisition of subsidiary		1,900
Conversion of Stock [Line Items]
Recognition upon acquisition of subsidiary		$ 1,900
McKesson Corporation, GEHE Pharma Handel
Conversion of Stock [Line Items]
Outstanding equity interest percentage		30.00%

Percentage of voting equity interests acquired at the acquisition date in the business combination.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
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-Publisher FASB
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Amount of decrease to net income for accretion of temporary equity to its redemption value to derive net income apportioned to common stockholders.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

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Redemption of temporary equity as the result of a triggering event associated with the temporary equity.

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The portion of net income or loss attributable to temporary equity interest.

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Temporary Equity, Acquisitions of Non-Controlling Interests

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