Equity method investments - Narrative (Details) - USD ($) shares in Thousands, $ in Millions				3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 08, 2023	Mar. 03, 2023	Dec. 15, 2022	May 31, 2024	May 31, 2023	May 31, 2024	May 31, 2023	Aug. 31, 2023
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investments						$ 847	$ 1,691
Cencora
Schedule of Equity Method Investments [Line Items]
Outstanding shares owned (in shares)				24,400		24,400		31,800
Ownership percentage				12.40%		12.40%		15.90%
Proceeds from sale of equity method investments				$ 400	$ 50	$ 1,600	3,100
Gain on sale of equity method investments				88	25	847	1,500
Other comprehensive (loss) income before reclassification adjustments				(10)	(2)	$ (39)	$ (152)
Period of reporting lag						2 months
Equity investment, exceeded its proportionate share of net assets				1,800		$ 1,800
Cencora | Not Designated as Hedging Instrument
Schedule of Equity Method Investments [Line Items]
Pledged collateral (in shares)						20,000		17,300
Cencora | Level 1
Schedule of Equity Method Investments [Line Items]
Fair market value of equity investment				$ 5,500		$ 5,500		$ 5,600
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]
Number of shares sold (in shares)	10,800	15,500
Proceeds from sale of equity method investments	$ 330	$ 469
Gain on sale of equity method investments		$ 154			$ 76