Commitments and Contingencies (Litigation and Environmental - Narrative) (Details) R$ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Sep. 30, 2010 BRL (R$)	Mar. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2024 BRL (R$) site	Mar. 31, 2024 USD ($) site	Sep. 30, 2023 USD ($)
Alleged Anticompete Litigation
Loss Contingencies [Line Items]
Civil fines imposed	R$ 179.2		$ 36,000,000
Provision for litigation			0
Maximum of loss contingency range subject to interest				R$ 179.2	$ 36,000,000
Environmental
Loss Contingencies [Line Items]
Approximate number of sites on which settlement has not been reached | site				27	27
Accrual for environmental loss contingencies					$ 62,200,000	$ 64,500,000
Accrual for environmental loss contingencies, maximum payout period				26 years	26 years
Environmental | Minimum
Loss Contingencies [Line Items]
Estimate of possible exposure from environmental loss contingencies					$ 62,000,000
Environmental | Maximum
Loss Contingencies [Line Items]
Estimate of possible exposure from environmental loss contingencies					$ 75,000,000
Disputed energy management charges
Loss Contingencies [Line Items]
Provision for litigation		$ 0	$ 0