XML 58 R38.htm IDEA: XBRL DOCUMENT
v3.8.0.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SALES TAX ACCOUNTING (Details) - USD ($) $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Jan. 01, 2018 | Jan. 01, 2017
Principal Transaction Revenue [Line Items] |  |  |  |
Sales tax | $ 13.3 | $ 11.2 |  |
NEW JERSEY |  |  |  |
Principal Transaction Revenue [Line Items] |  |  |  |
State sales tax, percent |  | 7.00% |  | 6.875%
Subsequent Event | NEW JERSEY |  |  |  |
Principal Transaction Revenue [Line Items] |  |  |  |
State sales tax, percent |  |  | 6.625% |

X
- Definition Sales Tax + References No definition available. + Details
Name: | njr_SalesTax
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition State Sales Tax, Percent + References No definition available. + Details
Name: | njr_StateSalesTaxPercent
Namespace Prefix: | njr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_PrincipleTransactionRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementGeographicalAxis=stpr_NJ
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |