Debt Instrument, Issuance, Number Of Tranches

No definition available.

Name:	sji_DebtInstrumentIssuanceNumberOfTranches
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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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

LONG-TERM DEBT (Details)	Apr. 03, 2020 USD ($)	Apr. 16, 2020 USD ($) Tranche	Mar. 31, 2020 USD ($)	Dec. 31, 2019	Sep. 23, 2019 USD ($)
Debt Instrument [Line Items]
Interest rate			7.50%	7.50%
Subsequent event
Debt Instrument [Line Items]
Repayments of debt	$ 200,000,000.0
Line of Credit
Debt Instrument [Line Items]
Total Facility			$ 1,210,000,000
SJI \| Line of Credit
Debt Instrument [Line Items]
Total Facility			800,000,000
SJI \| Variable Rate Note \| Notes Payable \| Subsequent event
Debt Instrument [Line Items]
Repayments of debt	50,000,000.0
SJG \| Line of Credit
Debt Instrument [Line Items]
Total Facility			210,000,000
SJG \| Senior Secured Notes, Series F, 2020 \| Senior Secured Notes \| Subsequent event
Debt Instrument [Line Items]
Principal amount issued		$ 525,000,000.0
Number of tranches \| Tranche		3
SJG \| Senior Secured Notes, Series F, 2020 \| Senior Secured Notes \| Tranche A \| Subsequent event
Debt Instrument [Line Items]
Principal amount issued		$ 150,000,000.0
Interest rate		3.28%
SJG \| Senior Secured Notes, Series F, 2020 \| Senior Secured Notes \| Tranche B \| Subsequent event
Debt Instrument [Line Items]
Principal amount issued		$ 250,000,000.0
Interest rate		3.93%
SJG \| Senior Secured Notes, Series F, 2020 \| Senior Secured Notes \| Tranche C \| Subsequent event
Debt Instrument [Line Items]
Principal amount issued		$ 125,000,000.0
Revolving Credit Facility \| SJI \| Line of Credit
Debt Instrument [Line Items]
Total Facility			50,000,000
Revolving Credit Facility \| SJI \| Line of Credit \| Subsequent event
Debt Instrument [Line Items]
Repayments of debt	50,000,000.0
Unsecured Term Loan \| Credit Agreement \| Subsequent event
Debt Instrument [Line Items]
Total Facility	200,000,000.0
Unsecured Term Loan \| SJI \| Unsecured Debt
Debt Instrument [Line Items]
Total Facility			$ 100,000,000		$ 100,000,000.0
Unsecured Term Loan \| SJI \| Unsecured Debt \| Subsequent event
Debt Instrument [Line Items]
Repayments of debt	100,000,000.0
Unsecured Term Loan \| SJI \| Credit Agreement \| Subsequent event
Debt Instrument [Line Items]
Total Facility	$ 200,000,000.0