XML 77 R56.htm IDEA: XBRL DOCUMENT
v3.10.0.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - AVAILABLE FOR SALE SECURITIES (Details) - USD ($) shares in Thousands, $ in Thousands | 1 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2015 | Mar. 31, 2018 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |
Proceeds from sale of available for sale securities, net |  |  | $ 6,616 | $ 6,639 | $ 0
Gain on sale of available-for-sale securities, pre-tax |  |  | 5,300 | 5,400 |
Gain on sale of available-for-sale securities, net of tax |  |  | 3,200 | 3,200 |
Impairment of available for sale securities |  | $ 17,800 |  |  |
Other than temporary impairment, net of tax |  | $ 14,800 |  |  |
Available for sale securities |  |  | 32,917 | 65,752 |
Unrealized gain |  |  | 4,700 | 12,800 |
Unrealized gain, net of tax |  |  | 3,400 | $ 7,700 |
Deferred gain, unamortized balance |  |  | $ (6,800) |  |
Common Units [Member] |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |
Ownership interest exchanged (in shares) | 1,840 |  |  |  |
Deferred gain | $ 24,600 |  |  |  |

X
- Definition Available-for-sale Securities, Realized Gain (Loss), Net of Tax + References No definition available. + Details
Name: | njr_AvailableforsaleSecuritiesRealizedGainLossNetofTax
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Deferred Gain (Loss), Unamortized Amount + References No definition available. + Details
Name: | njr_DeferredGainLossUnamortizedAmount
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Deferred Gain (Loss) on Exchange of Ownership Interest + References No definition available. + Details
Name: | njr_DeferredGainLossonExchangeofOwnershipInterest
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Other than Temporary Impairment Losses, Investments, Net of Tax + References No definition available. + Details
Name: | njr_OtherthanTemporaryImpairmentLossesInvestmentsNetofTax
Namespace Prefix: | njr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The number of units of other ownership interests issued in a limited partnership or master limited partnership. Does not include limited or general partners' ownership interests. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB TOPIC 4.F) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055 + Details
Name: | us-gaap_OtherOwnershipInterestsUnitsIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. + References No definition available. + Details
Name: | us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26853-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading. + References No definition available. + Details
Name: | us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=njr_CommonUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |