Supplemental information - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	May 31, 2020	May 31, 2019	Aug. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable from related party	$ 1,200		$ 1,200
Accumulated depreciation and amortization on property, plant, and equipment	12,100		11,300
Restricted cash (included in other current assets)	$ 175		184
Antidilutive securities excluded from EPS calculations (in shares)	20.5	17.0
Incremental antidilutive securities excluded from EPS calculations (in shares)	0.7
Trade Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 5,800		$ 6,000