Commitments and Contingencies (Pace, Piedmont, Pasadena Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2012	Sep. 30, 2008	Sep. 30, 2006
Loss Contingencies [Line Items]
Pretax environmental expense	$ 14,200,000	$ 12,800,000	$ 11,400,000
Pace, Florida
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	24,300,000					$ 42,000,000
Change in estimated exposure	0
Pace, Florida | Discontinued Operations
Loss Contingencies [Line Items]
Pretax environmental expense						42,000,000
Pace, Florida | Minimum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies						42,000,000
Pace, Florida | Maximum
Loss Contingencies [Line Items]
Estimate of possible exposure from environment loss contingencies						$ 52,000,000
Piedmont, South Carolina
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	14,700,000				$ 24,000,000
Piedmont, South Carolina | Discontinued Operations
Loss Contingencies [Line Items]
Pretax environmental expense					$ 24,000,000
Pasadena, Texas
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 11,800,000
Total anticipated exposure				$ 13,000,000