Commitments and Contingencies (Piedmont) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2008
Loss Contingencies [Line Items]
Pretax environmental expense	$ 28.3	$ 35.1	$ 37.1
Piedmont, Florida [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 18.1			$ 24.0
Years to complete environmental remediation	until 2017 to complete source area remediation and another 15 years thereafter to complete groundwater recovery
Change in estimated exposure	$ 0.0
Total anticipated exposure at this site				24.0
Segment Discontinued Operations Member | Piedmont, Florida [Member]
Loss Contingencies [Line Items]
Pretax environmental expense				$ 24.0