Divestitures - Summary of Asset Impairment, Disposal, and Exit Costs, Net (Details) $ in Millions	12 Months Ended
	Aug. 31, 2023 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment disposal and exit costs net	$ 46.7
Gunderson
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of long-lived assets	24.2
Gain (loss) on sale	14.4
Severance and exit costs	2.1
Total	40.7
Southwest Steel
Impaired Long-Lived Assets Held and Used [Line Items]
Gain (loss) on sale	9.7
Rayvag
Impaired Long-Lived Assets Held and Used [Line Items]
Gain (loss) on sale	$ (3.7)