Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013
Gas Utility Derivative Financial Instruments
Regulatory Assets
Gas utility unrealized gain (losses) on derivative financial instrument contracts	$ 2,389	$ (1,743)	$ 4,129
Electric Utility Forward Supply Contracts
Regulatory Assets
Net gains (losses) on electricity supply contracts	$ 358	$ (4,759)	$ (5,458)