Commitments and Contingencies (Litigation and Environmental Narrative) (Details) R$ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2010 BRL (R$)	Sep. 30, 2018 USD ($) site	Sep. 30, 2018 BRL (R$) site	Sep. 30, 2017 USD ($)
Alleged Anticompete Litigation
Loss Contingencies [Line Items]
Civil fines imposed	R$ 179.2	$ 44,000,000
Provision for litigation		0
Maximum of loss contingency range subject to interest		$ 44,000,000	R$ 179.2
Environmental
Loss Contingencies [Line Items]
Approximate number of sites on which settlement has not been reached | site		32	32
Accrual for environmental loss contingencies		$ 76,800,000		$ 83,600,000
Accrual for environmental loss contingencies, maximum payout period		30 years
Environmental | Minimum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies		$ 76,000,000
Environmental | Maximum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies		$ 90,000,000