Supplemental information - Depreciation and Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2021	May 31, 2020
Supplemental Cash Flow Elements [Abstract]
Depreciation expense	$ 352	$ 349	$ 1,042	$ 1,051
Intangible asset and other amortization	156	93	363	290
Total depreciation and amortization expense	$ 507	$ 443	$ 1,404	$ 1,341