-- None. No documentation exists for this element. --

Name:	sji_AffiliationsAbstract
Namespace Prefix:	sji
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

+ Details

Name:	sji_DebtRepaymentPeriodMaturityDate
Namespace Prefix:	sji
Data Type:	invest:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Disposal Group, Including Discontinued Operation, Anticipated Proceeds

+ Details

Name:	sji_DisposalGroupIncludingDiscontinuedOperationAnticipatedProceeds
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments in parties associated with the reporting entity net of guarantees to be paid by the reporting entity (which are included as liabilities on the balance sheet).

+ Details

Name:	sji_InvestmentInAffiliateNetOfGuarantees
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The maximum exposure to loss (i.e. risk) to the reporting entity should the affiliates (the parties associated with the reporting entity) become unable to continue operations.

+ Details

Name:	sji_MaximumexposuretoLossonaffiliates
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of net investments in, and advances to unconsolidated affiliates reported by an equity method investment of the entity.

+ Details

Name:	sji_NetAdvancesToUnconsolidatedAffiliates
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

+ Details

Name:	sji_NotesReceivableRelatedPartiesCurrentNoncurrent
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts due from parties associated with the reporting entity that are secured by property, plant and equipment owned by the party associated with the reporting entity, as evidenced by a written promise to pay.

+ Details

Name:	sji_NotesReceivableRelatedPartiesSecuredByPropertyPlantAndEquipment
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of notes receivable from affiliates, unsecured reported by an equity method investment of the entity. Amounts due from parties associated with the reporting entity, as evidenced by a written promise to pay, that are not secured by any collateral.

+ Details

Name:	sji_NotesReceivableRelatedPartiesUnsecured
Namespace Prefix:	sji
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Interest rate stated in the contractual debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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 Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: 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

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DISCONTINUED OPERATIONS AND AFFILATIONS 2 (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Affiliations [Abstract]
Investments in unconsolidated affiliates	$ 10.0		$ 60.9
Notes Receivable - affiliate	110.6	127.9
Notes receivable, secured by property, plant and equipment of affiliates	54.5
Interest accrual on secured notes receivable (in hundredths)	7.50%
Repayment period, latest date	2025
Notes receivable, unsecured	56.1
Net asset - included in investment in affiliates and other noncurrent liabilities	30.0
Combined equity contributions and the notes receivable - affiliate	143.6
Millennium Account Services [Member]
Affiliations [Abstract]
Equity interest (in hundredths)	50.00%
LVE Energy Partners, LLC (LVE) [Member]
Affiliations [Abstract]
Equity interest (in hundredths)	50.00%
Energenic US LLC [Member]
Affiliations [Abstract]
Equity interest (in hundredths)	50.00%
Potato Creek, LLC (Potato Creek) [Member]
Affiliations [Abstract]
Equity interest (in hundredths)	30.00%
Disposal Group, Including Discontinued Operation, Anticipated Proceeds	$ 9.0