Equity method investments - narrative (Details) - USD ($) $ in Millions			3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 11, 2024	Dec. 15, 2022	May 31, 2024	Feb. 28, 2022	Aug. 31, 2024	Aug. 31, 2023	Aug. 31, 2022
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investment					$ 1,520	$ 1,855	$ 559
Equity earnings (loss)					230	286	468
Share of OCI of equity method investments
Schedule of Equity Method Investments [Line Items]
Other comprehensive income (loss) before reclassification adjustments					$ (6)	$ 6	(326)
Cencora
Schedule of Equity Method Investments [Line Items]
Investment owned (in shares)					20,000,000.0	31,800,000
Ownership percentage					10.20%	15.90%
Proceeds from sale of equity method investments					$ 2,700	$ 3,400	900
Gain on sale of equity method investment					1,500	1,600	417
Other comprehensive income (loss) before reclassification adjustments					$ (63)	(160)	32
Time period of reporting lag					2 months
Equity investment, exceeded its proportionate share of net assets					$ 1,500
Cencora | Level 1
Schedule of Equity Method Investments [Line Items]
Fair value of assets					$ 4,800	5,600
Option Care Health
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of equity method investments						798	363
Gain on sale of equity method investment			$ 76			$ 186	145
Guangzhou Pharmaceuticals
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of equity method investments		$ 150
BrightSpring Health Services
Schedule of Equity Method Investments [Line Items]
Ownership percentage					18.00%
BrightSpring Health Services | Subsequent event
Schedule of Equity Method Investments [Line Items]
Ownership percentage	12.00%
Proceeds from sale of equity method investments	$ 129
Nanjing Pharmaceutical Company
Schedule of Equity Method Investments [Line Items]
Ownership percentage					11.00%
Guoda
Schedule of Equity Method Investments [Line Items]
Impairment of equity method investments and investments in equity and debt securities				$ 124	$ 364
VillageMD
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investment							2,200
Shields Health Solutions
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity method investment							$ 402