Line of Credit Facility, Number of Managing Banks

No definition available.

Name:	sji_LineofCreditFacilityNumberofManagingBanks
Namespace Prefix:	sji_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

- 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

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Balance Type:	na
Period Type:	duration

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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

- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_SeniorNotesMember
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Balance Type:
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- Details

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Data Type:	na
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Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=sji_UnsecuredTermLoanMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=sji_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=sji_SeriesE2017DueJanuary2047Member
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=sji_MarinaEnergyLlcMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=sji_NJEDAVariableRateDemandBondsMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=sji_NJEDAThermalEnergyFacilitiesRevenueBonds2001ProjectMember
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- Details

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- Details

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LONG-TERM DEBT (Details)	1 Months Ended
LONG-TERM DEBT (Details)	May 31, 2017 USD ($)	Jan. 31, 2017 USD ($) bank	Jun. 30, 2017 USD ($)
Debt Instrument [Line Items]
Interest rate			7.50%
Unsecured promissory notes \| Senior Notes
Debt Instrument [Line Items]
Principal amount issued			$ 16,000,000.0
Interest rate			2.71%
South Jersey Gas Company \| Unsecured term loan
Debt Instrument [Line Items]
Outstanding debt			$ 121,000,000
South Jersey Gas Company \| Credit Agreement \| Unsecured term loan
Debt Instrument [Line Items]
Letter of credit provided		$ 200,000,000.0
Credit agreement syndicated among number of banks \| bank		7
South Jersey Gas Company \| Medium-term notes \| Series E, 2017, Due January 2047
Debt Instrument [Line Items]
Principal amount issued		$ 200,000,000.0
Interest rate		3.00%
South Jersey Gas Company \| Loans payable \| Line of Credit
Debt Instrument [Line Items]
Pay down of multiple-draw term facility		$ 200,000,000
Marina \| Unsecured promissory notes \| NJEDA, Variable Rate Demand Bonds
Debt Instrument [Line Items]
Principal amount redeemed	$ 61,400,000
Marina \| Unsecured promissory notes \| NJEDA, Thermal Energy Facilities Revenue Bonds, 2001 Project
Debt Instrument [Line Items]
Principal amount redeemed	20,000,000
Marina \| Unsecured promissory notes \| NJEDA, Thermal Energy Facilities Federally Taxable Revenue Bonds, 2001 Project
Debt Instrument [Line Items]
Principal amount redeemed	25,000,000
Marina \| Unsecured promissory notes \| NJEDA, Thermal Energy Facilities Revenue Bonds, Series 2006A
Debt Instrument [Line Items]
Principal amount redeemed	$ 16,400,000