DERIVATIVES - Commodity Contract Commitments (Details)	12 Months Ended
	Aug. 31, 2021 MWh t
Aluminum | Long
Derivative [Line Items]
Commodity contract commitments	1,900
Copper | Long
Derivative [Line Items]
Commodity contract commitments	578
Copper | Short
Derivative [Line Items]
Commodity contract commitments	8,244
Electricity | Long
Derivative [Line Items]
Energy contract commitments | MWh	1,867,000