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NATURE OF THE BUSINESS (Details) | 6 Months Ended
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Mar. 31, 2015 customer
Steckman Ridge [Member] |
Nature of Business [Line Items] |
Equity method investment, ownership percentage | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = njr_SteckmanRidgeMember
Iroquois [Member] |
Nature of Business [Line Items] |
Equity method investment, ownership percentage | 5.53%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = njr_IroquoisMember
PennEast [Member] |
Nature of Business [Line Items] |
Equity method investment, ownership percentage | 20.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = njr_PennEastMember
NJNG [Member] |
Nature of Business [Line Items] |
Total retail customers | 512,000njr_TotalRetailCustomers / dei_LegalEntityAxis = njr_NjngMember

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- Definition Total number of retail customers specific to NJNG + References No definition available. + Details
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Details
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- Details
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