XML 120 R51.htm IDEA: XBRL DOCUMENT
v3.3.0.814

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, IMPAIRMENT OF LONG-LIVED ASSET (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013
Impaired Long-Lived Assets Held and Used [Line Items] |  |
Impairment loss | $ (6.4) |
Impairment loss, after tax | $ (3.8) |
OwnEnergy [Member] |  |
Impaired Long-Lived Assets Held and Used [Line Items] |  |
Investment |  | $ 8.8
Ownership interest rate |  | 18.70%

X
- Definition Asset Impairment Charges, net + References No definition available. + Details
Name: | njr_AssetImpairmentChargesnet
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity in the investee accounted for under the cost method of accounting. + References No definition available. + Details
Name: | njr_CostMethodInvestmentOwnershipPercentage
Namespace Prefix: | njr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51824106&loc=d3e2420-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 325 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6872867&loc=d3e40691-111596 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 325 -SubTopic 20 -Section 35 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=29638308&loc=d3e40346-111594 + Details
Name: | us-gaap_CostMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_ImpairedLongLivedAssetsHeldAndUsedLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=njr_OwnenergyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |