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DERIVATIVE INSTRUMENTS - BROKER MARGIN DEPOSITS (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Sep. 30, 2014
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Derivative [Line Items] |  |
Broker margin - Current assets | $ 44,046us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations | $ 27,339us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations
NJNG [Member] |  |
Derivative [Line Items] |  |
Broker margin - Current assets | 29,471us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = njr_NjngMember | 1,057us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = njr_NjngMember
NJRES [Member] |  |
Derivative [Line Items] |  |
Broker margin - Current assets | $ 14,575us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = njr_NjresMember | $ 26,282us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = njr_NjresMember

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- Details
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- Definition Amount of other receivables due from broker-dealers or clearing organizations. + References No definition available. + Details
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- Details
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