New accounting pronouncements - Effect of Lease 842 Adoption (Details) - USD ($) $ in Millions	Feb. 29, 2020	Sep. 01, 2019	Aug. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	$ 893		$ 1,118
Total current assets	18,909		18,700
Property, plant and equipment, net	13,482		13,478
Operating lease right-of-use assets	21,755		0
Intangible assets, net	10,929		10,876
Total assets	90,003		67,598
Operating lease obligation	2,278		0
Accrued expenses and other liabilities	5,408		5,474
Total current liabilities	28,662		25,769
Operating lease obligation	21,959		0
Deferred income taxes	1,637		1,785
Other non-current liabilities	2,786		4,795
Total non-current liabilities	37,007		17,678
Retained earnings	36,351		35,815
Total liabilities and equity	$ 90,003		67,598
Accounting Standards Update 2016-02
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 assets		21,600
Intangible assets, net		10,656
Total assets		89,122
Operating lease obligation		2,267
Accrued expenses and other liabilities		4,936
Total current liabilities		27,498
Operating lease obligation		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
Accounting Standards Update 2016-02 | Previously Reported
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
Total 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 | Adjustments
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 assets		21,600
Intangible assets, net		(220)
Total assets		21,524
Operating lease obligation		2,267
Accrued expenses and other liabilities		(538)
Total current liabilities		1,729
Operating lease obligation		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