Summary of major accounting policies - Effect of Lease 842 Adoption (Details) - USD ($) $ in Millions	Aug. 31, 2020	Sep. 01, 2019	Aug. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	$ 974		$ 1,118
Total current assets	18,073		18,700
Property, plant and equipment, net	13,342		13,478
Operating lease right-of-use asset	21,724	$ 22,000	0
Intangible assets, net	10,753		10,876
Total assets	87,174		67,598
Operating lease obligation - current	2,426		0
Accrued expenses and other liabilities	6,539		5,474
Current liabilities	27,070		25,769
Operating lease obligation - non-current	21,973		0
Deferred income taxes	1,498		1,785
Other non-current liabilities	3,294		4,795
Total non-current liabilities	38,968		17,678
Retained earnings	34,210		35,815
Total liabilities and equity	$ 87,174		67,598
Accounting standards update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets			1,118
Total current assets			18,700
Property, plant and equipment, net			13,478
Intangible assets, net			10,876
Total assets			67,598
Accrued expenses and other liabilities			5,474
Current liabilities			25,769
Deferred income taxes			1,785
Other non-current liabilities			4,795
Total non-current liabilities			17,678
Retained earnings			35,815
Total liabilities and equity			$ 67,598
Accounting standards update 2016-02 | Cumulative effect, period of adoption, adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		(123)
Total current assets		(123)
Property, plant and equipment, net		267
Operating lease right-of-use asset		21,600
Intangible assets, net		(220)
Total assets		21,524
Operating lease obligation - current		2,267
Accrued expenses and other liabilities		(538)
Current liabilities		1,729
Operating lease obligation - non-current		21,858
Deferred income taxes		(142)
Other non-current liabilities		(1,479)
Total non-current liabilities		20,237
Retained earnings		(442)
Total liabilities and equity		21,524
Accounting standards update 2016-02 | Cumulative effect, period of adoption, adjusted balance
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		995
Total current assets		18,577
Property, plant and equipment, net		13,745
Operating lease right-of-use asset		21,600
Intangible assets, net		10,656
Total assets		89,122
Operating lease obligation - current		2,267
Accrued expenses and other liabilities		4,936
Current liabilities		27,498
Operating lease obligation - non-current		21,858
Deferred income taxes		1,643
Other non-current liabilities		3,316
Total non-current liabilities		37,915
Retained earnings		35,373
Total liabilities and equity		$ 89,122