Supplemental information - Narrative (Details) - USD ($) shares in Millions, $ in Billions	3 Months Ended		9 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2023	May 31, 2022	Aug. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated depreciation and amortization on property, plant, and equipment	$ 13.0		$ 13.0		$ 12.8
Antidilutive securities excluded from EPS calculations (in shares)	17.4	17.4	17.8	17.2
Incremental common shares attributable to dilutive effect of share-based payment arrangements			3.3
Related Party
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables	$ 1.3		$ 1.3		1.1
Trade Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables	$ 4.6		$ 4.6		$ 4.0