Details of Selected Consolidated Balance Sheet Captions - Other Current Assets Detail Table (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Balance Sheet Related Disclosures [Abstract]
Deferred gas costs	$ 1,927	$ 65,714
Prepaid expenses	33,233	32,163
Materials and supplies	8,106	4,472
Assets from risk management activities	1,369	2,436
Other	1,420	1,536
Total	$ 46,055	$ 106,321

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Carrying amount as of the balance sheet date of capitalized gas costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of current assets classified as other.

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Amount of other miscellaneous assets expected to be realized or consumed within one year or operating cycle, if longer.

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No definition available.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Amount of consideration paid in advance for supplies that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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