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

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).

+ References

No definition available.

+ 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.

+ References

No definition available.

+ 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.

+ References

No definition available.

+ Details

Name:	sji_NetAdvancestoUnconsolidatedAffiliates
Namespace Prefix:	sji_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the 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

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
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 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

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsForAdvanceToAffiliate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from the sale of an investment interest in a joint venture that the reporting entity has not previously accounted for using consolidation or the equity method of accounting.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfInterestInJointVenture
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

DISCONTINUED OPERATIONS AND AFFILIATIONS 2 (Details) (USD $)	6 Months Ended				1 Months Ended					12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Energenic US LLC [Member]	Apr. 30, 2012 Energenic US LLC [Member] Marina Energy LLC [Member]	Dec. 31, 2010 Energenic US LLC [Member] Marina Energy LLC [Member]	Jun. 30, 2014 Potato Creek, LLC (Potato Creek) [Member]	Mar. 31, 2013 LVE Energy Partners, LLC (LVE) [Member]	Apr. 30, 2007 LVE Energy Partners, LLC (LVE) [Member] Marina Energy LLC [Member]	Dec. 31, 2013 LVE Energy Partners, LLC (LVE) [Member] LVE Energy Partners [Member] Marina Energy LLC [Member]
Affiliations [Abstract]
Equity interest (in hundredths)				50.00%		50.00%	30.00%	50.00%	50.00%
Advances to affiliates for acquisition	$ 1,922,000	$ 6,157,000			$ 35,400,000
Proceeds from sale of joint venture										57,900,000
Investments in unconsolidated affiliates	3,700,000	7,300,000
Notes Receivable - affiliate	45,300,000		48,800,000
Interest accrual on secured notes receivable (in hundredths)	7.50%
Net asset - included in investment in affiliates and other noncurrent liabilities	77,600,000
Combined equity contributions and the notes receivable - affiliate	$ 123,700,000