Utility Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013
Regulatory Assets
Gas utility unrealized gains (losses) on derivative financial instruments contracts	$ 0.7	$ (1.7)	$ (1.4)
Electric Utility Electric Supply Contracts
Regulatory Assets
Fair value of Electric Utility's electricity supply contracts	$ 0.8	$ (4.8)	$ (6.1)

Fair value of the assets less the liabilities of a derivative or group of derivatives.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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