Sales (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2021	May 31, 2020
Disaggregation of Revenue [Line Items]
Sales	$ 34,030	$ 30,364	$ 98,247	$ 91,612
Reportable Segments | United States
Disaggregation of Revenue [Line Items]
Sales	28,743	27,357	83,250	80,734
Reportable Segments | United States | Pharmacy
Disaggregation of Revenue [Line Items]
Sales	21,770	20,478	63,133	60,084
Reportable Segments | United States | Retail
Disaggregation of Revenue [Line Items]
Sales	6,973	6,879	20,117	20,650
Reportable Segments | International
Disaggregation of Revenue [Line Items]
Sales	5,288	3,008	14,998	10,878
Reportable Segments | International | Pharmacy
Disaggregation of Revenue [Line Items]
Sales	958	794	2,791	2,531
Reportable Segments | International | Retail
Disaggregation of Revenue [Line Items]
Sales	1,455	971	4,618	4,735
Reportable Segments | International | Wholesale
Disaggregation of Revenue [Line Items]
Sales	$ 2,875	$ 1,243	$ 7,588	$ 3,611