DERIVATIVE INSTRUMENTS - BROKER MARGIN DEPOSITS (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Natural Gas Distribution
Broker margin - Current assets	$ 2,661	$ 4,822
Energy Services
Broker margin - Current assets	$ 23,166	$ 42,822

Amount of other receivables due from broker-dealers or clearing organizations.

No definition available.

Name:	us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant