Segment reporting - results of operations of reportable segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Aug. 31, 2022	May 31, 2022	Feb. 28, 2022	Nov. 30, 2021	Aug. 31, 2021	May 31, 2021	Feb. 28, 2021	Nov. 30, 2020	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales	$ 32,449	$ 32,597	$ 33,756	$ 33,901	$ 34,262	$ 34,030	$ 32,779	$ 31,438	$ 132,703	$ 132,509	$ 121,982
Adjusted operating income									5,133	5,117	4,730
Depreciation and amortization									1,990	1,923	1,786
Capital expenditures									1,734	1,312	1,287
Acquisition-related amortization									(855)	(523)	(384)
Impairment of goodwill and intangible assets									(783)	(49)	(2,016)
Certain legal and regulatory accruals and settlements									(768)	(75)	0
Transformational cost management									(763)	(417)	(719)
Acquisition-related costs									(223)	(54)	(315)
Adjustments to equity earnings (loss) in AmerisourceBergen									(218)	(1,645)	(97)
LIFO provision									(135)	(13)	(95)
Store optimization									0	0	(53)
Store damage and inventory losses									0	0	(68)
Operating income									1,387	2,342	982
Reportable Segments | U.S. Retail Pharmacy
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales									109,078	112,005	107,701
Adjusted operating income									5,029	5,019	4,761
Depreciation and amortization									1,415	1,513	1,376
Capital expenditures									1,207	1,030	1,040
Reportable Segments | International
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales									21,830	20,505	14,281
Adjusted operating income									726	466	157
Depreciation and amortization									355	399	400
Capital expenditures									295	243	235
Reportable Segments | Walgreens health
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales									1,795	0	0
Adjusted operating income									(370)	(57)	0
Depreciation and amortization									211	1	0
Capital expenditures									218	34	0
Corporate and Other
Segment Reporting Information, Operating Income (Loss) [Abstract]
Adjusted operating income									(251)	(311)	(187)
Depreciation and amortization									9	10	10
Capital expenditures									$ 15	$ 5	$ 12