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Equity method investments - Narrative (Details) - USD ($) shares in Millions, $ in Millions					3 Months Ended		6 Months Ended
	Mar. 03, 2023	Dec. 15, 2022	Dec. 13, 2022	Nov. 10, 2022	Feb. 28, 2023	Nov. 30, 2021	Feb. 28, 2023	Feb. 28, 2022	Aug. 31, 2022
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investments							$ 1,512	$ 0
Impairment of equity method investments and investments in equity securities							$ 8	$ 190
Shields Health Solutions Parent, LLC
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investments						$ 402
VillageMD
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investments						$ 2,200
Impairment of equity method investments and investments in equity securities					$ 124
AmerisourceBergen
Schedule of Equity Method Investments [Line Items]
Outstanding shares owned (in shares)					33.7		33.7		52.9
Ownership percentage					16.70%		16.70%		25.40%
Number of shares sold (in shares)			6.0	13.2
Proceeds from sale of equity method investments			$ 984	$ 2,000
Gain on sale of equity method investments			492	969
Other comprehensive (loss) income before reclassification adjustments			$ 40	$ (110)
Period of reporting lag							2 months
Equity investment, exceeded its proportionate share of net assets					$ 2,600		$ 2,600
AmerisourceBergen \| Level 1
Schedule of Equity Method Investments [Line Items]
Fair market value of equity investment					$ 5,200		$ 5,200		$ 7,700
Guangzhou Pharmaceuticals
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of equity method investments		$ 150
Option Care Health
Schedule of Equity Method Investments [Line Items]
Percentage of outstanding common stock					14.40%		14.40%
Option Care Health \| Subsequent Event
Schedule of Equity Method Investments [Line Items]
Number of shares sold (in shares)	13.0
Proceeds from sale of equity method investments	$ 469
Percentage of outstanding common stock	6.00%
Option Care Health \| Subsequent Event \| Option Care Health
Schedule of Equity Method Investments [Line Items]
Share repurchase option (in shares)	2.5