Debt - Short and Long-Term Debt (Details) - USD ($) $ in Millions	May 31, 2020	Apr. 15, 2020	Aug. 31, 2019
Debt Instrument [Line Items]
Total short-term debt	$ 4,379		$ 5,738
Total long-term debt, less current portion	12,111		11,098
Unsecured Notes
Debt Instrument [Line Items]
Other	24		25
Total long-term debt, less current portion	12,111		11,098
Unsecured Notes | 3.200% unsecured notes due 2030
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 497		0
Stated interest rate	3.20%	3.20%
Unsecured Notes | 4.100% unsecured notes due 2050
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 990		0
Stated interest rate	4.10%	4.10%
Unsecured Notes | 2.875% unsecured Pound sterling notes due 2020
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 0		488
Stated interest rate	2.875%
Unsecured Notes | 3.450% unsecured notes due 2026
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,891		1,890
Stated interest rate	3.45%
Unsecured Notes | 4.650% unsecured notes due 2046
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 591		591
Stated interest rate	4.65%
Unsecured Notes | 3.300% unsecured notes due 2021
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,248		1,247
Stated interest rate	3.30%
Unsecured Notes | 3.800% unsecured notes due 2024
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,993		1,992
Stated interest rate	3.80%
Unsecured Notes | 4.500% unsecured notes due 2034
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 495		495
Stated interest rate	4.50%
Unsecured Notes | 4.800% unsecured notes due 2044
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,493		1,492
Stated interest rate	4.80%
Unsecured Notes | 3.600% unsecured Pound sterling notes due 2025
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 369		365
Stated interest rate	3.60%
Unsecured Notes | 2.125% unsecured Euro notes due 2026
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 830		824
Stated interest rate	2.125%
Unsecured Notes | 3.100% unsecured notes due 2022
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 1,198		1,197
Stated interest rate	3.10%
Unsecured Notes | 4.400% unsecured notes due 2042
Debt Instrument [Line Items]
Carrying value of notes, net of unamortized discount and interest rate swap FMV adjustment	$ 493		493
Stated interest rate	4.40%
Commercial Paper
Debt Instrument [Line Items]
Total short-term debt	$ 2,193		2,400
Credit facilities
Debt Instrument [Line Items]
Total short-term debt	1,139		1,624
Notes payable to banks | 2.700% unsecured notes due 2019
Debt Instrument [Line Items]
Total short-term debt	$ 0		1,250
Stated interest rate	2.70%
Notes payable to banks | 2.875% unsecured Pound sterling notes due 2020
Debt Instrument [Line Items]
Total short-term debt	$ 494		0
Other
Debt Instrument [Line Items]
Total short-term debt	$ 554		$ 464