Debt - short and long-term debt (Details)		12 Months Ended
	Apr. 26, 2021 USD ($)	Aug. 31, 2021 USD ($)	Aug. 31, 2020 USD ($)	Aug. 31, 2019 USD ($)	Sep. 18, 2021 USD ($)	Aug. 31, 2021 GBP (£)	Aug. 31, 2021 EUR (€)	Apr. 23, 2021 USD ($)	Apr. 09, 2021 USD ($)	Oct. 20, 2020 GBP (£)	Apr. 15, 2020 USD ($)
Debt Instrument [Line Items]
Total short-term debt		$ 1,305,000,000	$ 3,265,000,000
Other		29,000,000	24,000,000
Total long-term debt, less current portion		7,675,000,000	12,203,000,000
Long-term debt purchased and retired		15,257,000,000	21,414,000,000	$ 10,461,000,000
Loss on early extinguishment of debt		$ 414,000,000	0	$ 0
2.875% unsecured pound sterling notes due 2020
Debt Instrument [Line Items]
Face amount | £						£ 700,000,000
Stated interest rate (as a percent)		2.875%				2.875%	2.875%			2.875%
Total short-term debt		$ 0	533,000,000
Debt redeemed | £										£ 400,000,000
3.300% unsecured notes due 2021
Debt Instrument [Line Items]
Face amount		$ 8,000,000,000
Stated interest rate (as a percent)		3.30%				3.30%	3.30%
Total short-term debt		$ 1,250,000,000	0
3.300% unsecured notes due 2021 | Forecast
Debt Instrument [Line Items]
Debt redeemed					$ 1,250,000,000
Other
Debt Instrument [Line Items]
Total short-term debt		56,000,000	144,000,000
$1.5 billion debt issuance
Debt Instrument [Line Items]
Face amount											$ 1,500,000,000
Unsecured notes
Debt Instrument [Line Items]
Long-term debt purchased and retired	$ 3,300,000,000
Weighted average interest rate of long-term debt purchased and retired	4.02%
Loss on early extinguishment of debt	$ 414,000,000	$ 387,000,000
Redemption premiums paid in cash	386,000,000
Unsecured notes | 3.300% unsecured notes due 2021
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.30%				3.30%	3.30%
Long-term debt		$ 0	1,248,000,000
Unsecured notes | $1.5 billion debt issuance
Debt Instrument [Line Items]
Face amount		$ 1,500,000,000
Unsecured notes | 3.200% unsecured notes due 2030
Debt Instrument [Line Items]
Face amount											$ 500,000,000
Stated interest rate (as a percent)		3.20%				3.20%	3.20%				3.20%
Long-term debt		$ 497,000,000	497,000,000
Unsecured notes | 4.100% unsecured notes due 2050
Debt Instrument [Line Items]
Face amount											$ 1,000,000,000
Stated interest rate (as a percent)		4.10%				4.10%	4.10%				4.10%
Long-term debt		$ 792,000,000	990,000,000
Debt redeemed	$ 200,000,000
Unsecured notes | Total $6 billion note issuance
Debt Instrument [Line Items]
Face amount		$ 6,000,000,000
Unsecured notes | 3.450% unsecured notes due 2026
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.45%				3.45%	3.45%
Long-term debt		$ 1,442,000,000	1,891,000,000
Unsecured notes | 4.650% unsecured notes due 2046
Debt Instrument [Line Items]
Stated interest rate (as a percent)		4.65%				4.65%	4.65%
Long-term debt		$ 318,000,000	591,000,000
Unsecured notes | Total $8 billion note issuance
Debt Instrument [Line Items]
Face amount		$ 8,000,000,000
Unsecured notes | 3.800% unsecured notes due 2024
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.80%				3.80%	3.80%
Long-term debt		$ 1,154,000,000	1,993,000,000
Unsecured notes | 4.500% unsecured notes due 2034
Debt Instrument [Line Items]
Stated interest rate (as a percent)		4.50%				4.50%	4.50%
Long-term debt		$ 301,000,000	496,000,000
Unsecured notes | 4.800% unsecured notes due 2044
Debt Instrument [Line Items]
Stated interest rate (as a percent)		4.80%				4.80%	4.80%
Long-term debt		$ 868,000,000	1,493,000,000
Unsecured notes | Total £700 million note issuance
Debt Instrument [Line Items]
Face amount | £						£ 700,000,000
Unsecured notes | 3.600% unsecured Pound sterling notes due 2025
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.60%				3.60%	3.60%
Long-term debt		$ 408,000,000	398,000,000
Unsecured notes | Total €750 million note issuance
Debt Instrument [Line Items]
Face amount | €							€ 750,000,000
Unsecured notes | 2.125% unsecured Euro notes due 2026
Debt Instrument [Line Items]
Stated interest rate (as a percent)		2.125%				2.125%	2.125%
Long-term debt		$ 873,000,000	891,000,000
Unsecured notes | Total $4 billion note issuance
Debt Instrument [Line Items]
Face amount		$ 4,000,000,000
Unsecured notes | 3.100% unsecured notes due 2022
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.10%				3.10%	3.10%
Long-term debt		$ 731,000,000	1,198,000,000
Unsecured notes | 4.400% unsecured notes due 2042
Debt Instrument [Line Items]
Stated interest rate (as a percent)		4.40%				4.40%	4.40%
Long-term debt		$ 263,000,000	493,000,000
Term loan | April 2021 credit agreement | Credit facilities
Debt Instrument [Line Items]
Maximum borrowing capacity								$ 3,800,000,000	$ 2,800,000,000
Commercial paper
Debt Instrument [Line Items]
Total short-term debt		0	1,517,000,000
Credit facilities
Debt Instrument [Line Items]
Total short-term debt		$ 0	$ 1,071,000,000