Sales (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Aug. 31, 2021	May 31, 2021	Feb. 28, 2021	Nov. 30, 2020	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
Disaggregation of Revenue [Line Items]
Sales	$ 34,262	$ 34,030	$ 32,779	$ 31,438	$ 30,371	$ 30,364	$ 31,336	$ 29,912	$ 132,509	$ 121,982	$ 120,074
Reportable Segments | United States
Disaggregation of Revenue [Line Items]
Sales									112,005	107,701	104,532
Reportable Segments | United States | Pharmacy
Disaggregation of Revenue [Line Items]
Sales									84,892	80,481	77,299
Reportable Segments | United States | Retail
Disaggregation of Revenue [Line Items]
Sales									27,113	27,220	27,233
Reportable Segments | International
Disaggregation of Revenue [Line Items]
Sales									20,505	14,281	15,542
Reportable Segments | International | Pharmacy
Disaggregation of Revenue [Line Items]
Sales									3,808	3,503	3,653
Reportable Segments | International | Retail
Disaggregation of Revenue [Line Items]
Sales									6,225	5,902	7,177
Reportable Segments | International | Wholesale
Disaggregation of Revenue [Line Items]
Sales									$ 10,472	$ 4,876	$ 4,713