XML 61 R38.htm IDEA: XBRL DOCUMENT
v3.10.0.1

NATURE OF THE BUSINESS (Details) | 3 Months Ended
--- | ---
Dec. 31, 2018 subsidiary customer
Steckman Ridge |
Nature of Business [Line Items] |
Ownership percentage | 50.00%
PennEast |
Nature of Business [Line Items] |
Ownership percentage | 20.00%
Natural Gas Distribution |
Nature of Business [Line Items] |
Total retail customers | customer | 543,800
NJR Retail Holdings Corporation |
Nature of Business [Line Items] |
Number of principal subsidiaries | subsidiary | 2

X
- Definition [Line Items] for Nature of Business [Table] + References No definition available. + Details
Name: | njr_NatureofBusinessLineItems
Namespace Prefix: | njr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Principal Subsidiaries + References No definition available. + Details
Name: | njr_NumberofPrincipalSubsidiaries
Namespace Prefix: | njr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total number of retail customers specific to NJNG + References No definition available. + Details
Name: | njr_TotalRetailCustomers
Namespace Prefix: | njr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=njr_SteckmanRidgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=njr_PennEastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=njr_NjngMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=njr_NJRRetailHoldingsCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |