Supplemental information - Depreciation and Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018	Aug. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 379	$ 358	$ 1,096	$ 1,040
Intangible asset and other amortization	142	84	415	260
Total depreciation and amortization expense	522	$ 442	1,512	$ 1,300
Accumulated depreciation and amortization on property, plant, and equipment	$ 11,200		$ 11,200		$ 10,500