Commitments and Contingencies (Litigation and Environmental Narrative) (Details) BRL in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2010 BRL	Sep. 30, 2017 USD ($) site	Sep. 30, 2017 BRL site	Sep. 30, 2016 USD ($)
Alleged Anticompete Litigation
Loss Contingencies [Line Items]
Civil fines imposed	BRL 179.2	$ 57,000,000
Provision for litigation		0
Maximum of loss contingency range subject to interest		$ 57,000,000	BRL 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		$ 83,600,000		$ 81,400,000
Accrual for environmental loss contingencies, maximum payout period		30 years
Environmental | Minimum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies		$ 83,000,000
Environmental | Maximum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies		$ 97,000,000