LONG-TERM DEBT (Details) - USD ($)		1 Months Ended				12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Aug. 31, 2015	Jun. 30, 2015	Dec. 31, 2015	Oct. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Aug. 31, 2014	Jun. 30, 2014
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1]	$ 1,035,848,000				$ 1,035,848,000		$ 1,009,400,000
Less Current Maturities	[1]	(29,454,000)				(29,454,000)		(149,909,000)
Total Long-Term Debt	[1]	1,006,394,000				1,006,394,000		859,491,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2016		29,454,000				29,454,000
2017		172,558,000				172,558,000
2018		40,667,000				40,667,000
2019		260,783,000				260,783,000
2020		74,476,000				74,476,000
Amount of facility		610,000,000				610,000,000
Guarantor obligations		$ 79,300,000				$ 79,300,000
Senior Notes [Member] | Series Due Jun 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage											3.05%
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt											$ 60,000,000
Senior Notes [Member] | Series Due Aug 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage										3.05%
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt										$ 30,000,000
Senior Notes [Member] | Series Due Sept 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage									3.05%
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt									$ 50,000,000
Senior Notes [Member] | Series Due June 2019, Floating Rate [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		1.93%				1.93%
Amount of debt											40,000,000
Senior Notes [Member] | Series Due Sept 2019, Floating Rate [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt									$ 60,000,000
Senior Notes [Member] | June 2014 Note Purchase Agreement [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt											240,000,000
Medium-term Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Maximum borrowing capacity		$ 400,000,000.0				$ 400,000,000.0
South Jersey Gas Company [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of facility		$ 210,000,000				$ 210,000,000
South Jersey Gas Company [Member] | Series Due 2015, 5.387% [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		5.387%				5.387%
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt retired				$ 10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2015, 5.387% [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[2],[3]	$ 0				$ 0		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2016, 5.437% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		5.437%				5.437%
Total Long-Term Debt Outstanding	[1],[3]	$ 10,000,000				$ 10,000,000		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2016, 4.6% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.60%				4.60%
Total Long-Term Debt Outstanding	[1],[3]	$ 17,000,000				$ 17,000,000		17,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2017, 4.657% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.657%				4.657%
Total Long-Term Debt Outstanding	[1],[3]	$ 15,000,000				$ 15,000,000		15,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2018, 7.97% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		7.97%				7.97%
Total Long-Term Debt Outstanding	[1],[3]	$ 10,000,000				$ 10,000,000		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2018, 7.125% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		7.125%				7.125%
Total Long-Term Debt Outstanding	[1],[3]	$ 20,000,000				$ 20,000,000		20,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2019, 5.587% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		5.587%				5.587%
Total Long-Term Debt Outstanding	[1],[3]	$ 10,000,000				$ 10,000,000		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2024, 3.00% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.00%				3.00%
Total Long-Term Debt Outstanding	[1],[3]	$ 50,000,000				$ 50,000,000		50,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2024, 3.03% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.03%				3.03%
Total Long-Term Debt Outstanding	[1],[3]	$ 35,000,000				$ 35,000,000		35,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2025, 3.63% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.63%				3.63%
Repayments of Debt		$ 900,000
Total Long-Term Debt Outstanding	[1],[3],[4]	$ 9,091,000				$ 9,091,000		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2026, 4.84% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.84%				4.84%
Total Long-Term Debt Outstanding	[1],[3]	$ 15,000,000				$ 15,000,000		15,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2026, 4.93% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.93%				4.93%
Total Long-Term Debt Outstanding	[1],[3]	$ 45,000,000				$ 45,000,000		45,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2027, 4.03% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.03%				4.03%
Total Long-Term Debt Outstanding	[1],[3]	$ 45,000,000				$ 45,000,000		45,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2030, 4.01% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.01%				4.01%
Total Long-Term Debt Outstanding	[1],[3]	$ 50,000,000				$ 50,000,000		50,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due January 2030, 4.23% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.23%				4.23%
Total Long-Term Debt Outstanding	[1],[3]	$ 30,000,000				$ 30,000,000		30,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2032, 3.74% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.74%				3.74%
Total Long-Term Debt Outstanding	[1],[3]	$ 35,000,000				$ 35,000,000		35,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2033, 5.55% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		5.55%				5.55%
Total Long-Term Debt Outstanding	[1],[3]	$ 32,000,000				$ 32,000,000		32,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2034, 6.213% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		6.213%				6.213%
Total Long-Term Debt Outstanding	[1],[3]	$ 10,000,000				$ 10,000,000		10,000,000
South Jersey Gas Company [Member] | First Mortgage Bonds [Member] | Series Due 2035, 5.45% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		5.45%				5.45%
Total Long-Term Debt Outstanding	[1],[3]	$ 10,000,000				$ 10,000,000		10,000,000
South Jersey Gas Company [Member] | Unsecured debt [Member] | Series A. 2006 Bonds [Member]
Debt Instrument [Line Items]
Repayments of Debt			$ 100,000
Total Long-Term Debt Outstanding	[1],[5]	$ 24,900,000				$ 24,900,000		25,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		0.03%				0.03%
South Jersey Gas Company [Member] | Loans Payable [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[6]	$ 139,000,000				$ 139,000,000		59,000,000
Average interest rate		1.17%				1.17%
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of facility											$ 200,000,000
Marina Energy LLC [Member] | Energenic US LLC [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Equity interest		50.00%				50.00%
Marina Energy LLC [Member] | Unsecured debt [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding		$ 61,400,000				$ 61,400,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Outstanding amount of note not fixed by interest rate derivatives		$ 39,000,000				$ 39,000,000
Fixed interest rate		4.22%				4.22%
Marina Energy LLC [Member] | Unsecured debt [Member] | Series A. 2031 Bonds [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[7]	$ 20,000,000				$ 20,000,000		20,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		0.04%				0.04%
Marina Energy LLC [Member] | Unsecured debt [Member] | Series B. 2021 Bonds [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[7]	$ 25,000,000				$ 25,000,000		25,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		0.47%				0.47%
Marina Energy LLC [Member] | Unsecured debt [Member] | Series A. 2036 [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[7]	$ 16,400,000				$ 16,400,000		16,400,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		0.04%				0.04%
South Jersey Industries Inc [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of facility		$ 400,000,000				$ 400,000,000
South Jersey Industries Inc [Member] | Unsecured debt [Member] | Term Loan Due 2015 [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[8]	$ 0				$ 0		50,000,000
South Jersey Industries Inc [Member] | Unsecured debt [Member] | Term Loan Due 2015 [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding							$ 50,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate at period end		1.28%				1.28%
South Jersey Industries Inc [Member] | Unsecured debt [Member] | Term Loan Due 2020 [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[8]	$ 50,000,000				$ 50,000,000		0
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series A Notes Due 2015, 2.39% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		2.39%				2.39%
Total Long-Term Debt Outstanding	[1],[9]	$ 0				$ 0		64,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Amount of debt retired					$ 64,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series B Notes Due 2017, 2.71% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		2.71%				2.71%
Total Long-Term Debt Outstanding	[1]	$ 16,000,000				$ 16,000,000		16,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series Due Jun 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.05%				3.05%
Total Long-Term Debt Outstanding	[1],[10]	$ 60,000,000				$ 60,000,000		60,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series Due Aug 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.05%				3.05%
Total Long-Term Debt Outstanding	[1],[10]	$ 30,000,000				$ 30,000,000		30,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series Due Sept 2019, 3.05% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.05%				3.05%
Total Long-Term Debt Outstanding	[1],[10]	$ 50,000,000				$ 50,000,000		50,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series C Notes Due 2022, 3.46% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		3.46%				3.46%
Total Long-Term Debt Outstanding	[1]	$ 35,000,000				$ 35,000,000		35,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series Due June 2019, Floating Rate [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[10]	40,000,000				40,000,000		40,000,000
South Jersey Industries Inc [Member] | Senior Notes [Member] | Series Due Sept 2019, Floating Rate [Member]
Debt Instrument [Line Items]
Total Long-Term Debt Outstanding	[1],[10]	$ 60,000,000				$ 60,000,000		60,000,000
ACB Energy Partners, LLC [Member] | Loan and Security Agreement [Member] | Loan and Security Agreement Due 2021, 7.60% [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		7.60%				7.60%
Total Long-Term Debt Outstanding	[1],[11]	$ 12,735,000				$ 12,735,000		0
Long-term Debt, Fiscal Year Maturity [Abstract]
Maximum borrowing capacity		$ 16,000,000				$ 16,000,000
AC Landfill Energy, LLC [Member] | Debt Agreement [Member] | Debt Agreement Due 2020, 4.83% Agreement 1 [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.83%				4.83%
Total Long-Term Debt Outstanding	[1],[12]	$ 3,551,000				$ 3,551,000		0
SC Landfill Energy, LLC [Member] | Debt Agreement [Member] | Debt Agreement Due 2020, 4.83% Agreement 2 [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.83%				4.83%
Total Long-Term Debt Outstanding	[1],[12]	$ 1,738,000				$ 1,738,000		0
SX Landfill Energy, LLC [Member] | Debt Agreement [Member] | Debt Agreement Due 2020, 4.83% Agreement 3 [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.83%				4.83%
Total Long-Term Debt Outstanding	[1],[12]	$ 3,433,000				$ 3,433,000		0
ACLE, SCLE and SXLE [Member] | Debt Agreement [Member]
Debt Instrument [Line Items]
Stated interest rate percentage		4.83%				4.83%
Total Long-Term Debt Outstanding		$ 8,700,000				$ 8,700,000		4,700,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Maximum borrowing capacity		$ 10,000,000				$ 10,000,000
SJI's percentage of guarantee of the outstanding debt						50.00%
Guarantor obligations								$ 300,000

[1] Long-term debt maturities and sinking funds requirements for the succeeding five years are as follows (in thousands): 2016, $29,454; 2017, $172,558; 2018,$40,667; 2019,$260,783; and 2020, $74,476.

[2] In August 2015, SJG retired $10.0 million aggregate principal amount of 5.387% Medium Term Notes (MTN's) at maturity.

[3] The First Mortgage dated October 1, 1947, as supplemented, securing the First Mortgage Bonds constitutes a direct first mortgage lien on substantially all utility plant.

[4] In December 2015, SJG paid $0.9 million toward the principal amount of 3.63% MTN's due December 2025.

[5] In September 2015, SJG paid $0.1 million toward the principal amount of variable rate demand bonds due February 2036. These variable rate demand bonds bear interest at a floating rate that resets weekly. The interest rate as of December 31, 2015 was 0.03%. Liquidity support on these bonds is provided under a separate letter of credit facility that expires in August 2018. These bonds contain no financial covenants.

[6] In June 2014, SJG entered into a $200.0 million multiple-draw term facility offered by a syndicate of banks which expires in June 2017. SJG can draw under this facility through June 2016 and this facility bears interest at a floating rate based on LIBOR plus a spread determined by SJG's credit ratings. As of December 31, 2015, SJG had borrowed an aggregate $139.0 million under this facility at an average interest rate of 1.17% and the proceeds were used to pay down short-term debt.

[7] Marina has issued $61.4 million of unsecured variable-rate revenue bonds through the New Jersey Economic Development Authority (NJEDA). The variable rates at December 31, 2015 for the Series A 2001, Series B 2001, and Series A 2006 bonds were 0.04%, 0.47% and 0.04% respectively. The interest rate on all but $39.0 million of the bonds has been effectively fixed via interest rate swaps at 4.22% until January 2026. These bonds contain no financial covenants. Liquidity support on these bonds is provided under a letter of credit facility from a commercial bank that expires in March, 2016. The Company has plans to renew this letter of credit facility upon expiration.

[8] In October 2015, SJI entered into an unsecured, variable-rate term loan of $50.0 million, which matures in October 2020. This agreement replaced existing facilities that expired in October 2015. The variable rate at December 31, 2015 was 1.28%.

[9] In June 2015, SJI redeemed at maturity $64.0 million aggregate principal amount of 2.39% Senior Notes.

[10] In June 2014, SJI entered into a Note Purchase Agreement that provided for SJI to issue an aggregate of $240.0 million of medium term notes, all of which were issued as follows: (a) in June 2014, SJI issued $60.0 million aggregate principal amount of 3.05% Senior Notes due June 2019, and $40.0 million aggregate principal amount of Floating Rate Senior Notes due June 2019; (b) in August 2014, SJI issued $30.0 million aggregate principal amount of 3.05% Senior Notes due August 2019; and (c) in September 2014, SJI issued $50.0 million aggregate principal amount of 3.05% Senior Notes due September 2019, and $60.0 million aggregate principal amount of Floating Rate Senior Notes due September 2019. At December 31, 2015, the floating rate was 1.93%.

[11] ACB has a Loan and Security Agreement (“LSA”) with a third party to borrow up to $16.0 million. Under the LSA, ACB pays principal and interest (at a fixed rate of 7.60%) in equal quarterly installments that began in February 2011 and run through February 2021. As of December 31, 2014, ACB was a wholly-owned subsidiary of Energenic, of which Marina has a 50% equity interest. In December 2015, ACB became a wholly-owned subsidiary of Marina (see Note 3); as such, the remaining outstanding debt of $12.7 million is included on the consolidated balance sheets as of December 31, 2015. The remaining debt was paid in January 2016 (see Note 19).

[12] ACLE, SCLE and SXLE (the "Other Energy Projects") have long-term debt agreements with a third party to borrow up to $10.0 million. Under the debt agreement, the Other Energy Projects pay principal and interest (at a fixed rate of 4.83%) in equal installments that began December 2013 and run through December 2020. As of December 31, 2014, the Other Energy Projects were wholly-owned subsidiaries of Energenic, of which Marina had a 50% equity interest. SJI had agreements to guarantee 50% of the outstanding debt, which was $4.7 million as of December 31, 2014, and the Company had recorded $0.3 million for the fair value of the guarantees on the consolidated balance sheets as of December 31, 2014. In December 2015, the Other Energy Projects became wholly-owned subsidiaries of Marina (see Note 3); as such, the remaining outstanding debt of $8.7 million is included on the consolidated balance sheets as of December 31, 2015.