Equity method investments - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023	Aug. 31, 2023
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investments			$ 758	$ 1,512
Cencora
Schedule of Equity Method Investments [Line Items]
Outstanding shares owned (in shares)	26.3		26.3		31.8
Ownership percentage	13.50%		13.50%		15.90%
Proceeds from Sale of Equity Method Investments	$ 992	$ 984	$ 1,200	3,000
Gain on sale of equity method investments	619	492	758	1,500
Other comprehensive income (loss) before reclassification adjustments	(20)	$ (40)	$ (28)	$ (150)
Period of reporting lag			2 months
Equity investment, exceeded its proportionate share of net assets	2,100		$ 2,100
Cencora | Not Designated as Hedging Instrument
Schedule of Equity Method Investments [Line Items]
Pledged collateral (in shares)			20.0		17.3
Cencora | Level 1
Schedule of Equity Method Investments [Line Items]
Fair market value of equity investment	$ 6,200		$ 6,200		$ 5,600