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Commitments And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012
Site Contingency [Line Items]
Estimated minimum liability for environmental remediation	$ 16.3
Estimated maximum liability for environmental remediation	21.9
Former Manufactured Gas Plant Site [Member]
Site Contingency [Line Items]
Estimated minimum liability for environmental remediation	$ 14.0
Rate recovery period	11 years

The estimated maximum amount of possible loss from the contingency.

The estimated minimum amount of possible loss from the contingency.