FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / decatherm	Dec. 31, 2018 USD ($) $ / decatherm
Assets
Available-for-Sale Securities	$ 40	$ 41
Changes in significant unobservable inputs [Roll forward]
Balance at beginning of period	16,061	3,110
Other changes in fair value from continuing and new contracts, net	19,688	14,418
Settlements	(18,175)	(1,467)
Balance at end of period	17,574	16,061
Measurement at fair value on recurring basis
Assets
Available-for-Sale Securities	40	41
Derivatives - Energy Related Assets	60,135	61,190
Assets	60,175	61,231
Liabilities
Derivatives - Energy Related Liabilities	50,171	31,390
Derivatives - Other	12,660	7,873
Liabilities	62,831	39,263
Measurement at fair value on recurring basis | Level 1
Assets
Available-for-Sale Securities	40	41
Derivatives - Energy Related Assets	16,931	9,955
Assets	16,971	9,996
Liabilities
Derivatives - Energy Related Liabilities	34,446	7,291
Derivatives - Other	0	0
Liabilities	34,446	7,291
Measurement at fair value on recurring basis | Level 2
Assets
Available-for-Sale Securities	0	0
Derivatives - Energy Related Assets	17,841	23,429
Assets	17,841	23,429
Liabilities
Derivatives - Energy Related Liabilities	7,936	12,354
Derivatives - Other	12,660	7,873
Liabilities	20,596	20,227
Measurement at fair value on recurring basis | Level 3
Assets
Available-for-Sale Securities	0	0
Derivatives - Energy Related Assets	25,363	27,806
Assets	25,363	27,806
Liabilities
Derivatives - Energy Related Liabilities	7,789	11,745
Derivatives - Other	0	0
Liabilities	7,789	11,745
South Jersey Gas Company
Changes in significant unobservable inputs [Roll forward]
Balance at beginning of period	4,928	2,052
Other changes in fair value from continuing and new contracts, net	5,035	4,928
Settlements	(4,928)	(2,052)
Balance at end of period	5,035	4,928
South Jersey Gas Company | Measurement at fair value on recurring basis
Assets
Derivatives - Energy Related Assets	16,909	5,479
Assets	16,909	5,479
Liabilities
Derivatives - Energy Related Liabilities	14,766	2,189
Derivatives - Other	7,856	5,867
Liabilities	22,622	8,056
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 1
Assets
Derivatives - Energy Related Assets	11,860	348
Assets	11,860	348
Liabilities
Derivatives - Energy Related Liabilities	14,565	1,035
Derivatives - Other	0	0
Liabilities	14,565	1,035
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 2
Assets
Derivatives - Energy Related Assets	0	126
Assets	0	126
Liabilities
Derivatives - Energy Related Liabilities	187	1,077
Derivatives - Other	7,856	5,867
Liabilities	8,043	6,944
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 3
Assets
Derivatives - Energy Related Assets	5,049	5,005
Assets	5,049	5,005
Liabilities
Derivatives - Energy Related Liabilities	14	77
Derivatives - Other	0	0
Liabilities	14	77
Natural Gas (in MMdts) | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	21,645	20,706
Liabilities	$ 4,333	$ 8,976
Natural Gas (in MMdts) | Level 3 | Forward Contract | Minimum
Liabilities
Forward price (in USD per dt) | $ / decatherm	1.57	1.56
Natural Gas (in MMdts) | Level 3 | Forward Contract | Maximum
Liabilities
Forward price (in USD per dt) | $ / decatherm	7.28	9.00
Natural Gas (in MMdts) | Level 3 | Forward Contract | Weighted Average
Liabilities
Forward price (in USD per dt) | $ / decatherm	2.38	3.12
Natural Gas (in MMdts) | South Jersey Gas Company | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	$ 5,049	$ 5,005
Liabilities	$ 14	$ 77
Natural Gas (in MMdts) | South Jersey Gas Company | Level 3 | Forward Contract | Minimum
Liabilities
Forward price (in USD per dt) | $ / decatherm	1.85	3.13
Natural Gas (in MMdts) | South Jersey Gas Company | Level 3 | Forward Contract | Maximum
Liabilities
Forward price (in USD per dt) | $ / decatherm	3.61	6.00
Natural Gas (in MMdts) | South Jersey Gas Company | Level 3 | Forward Contract | Weighted Average
Liabilities
Forward price (in USD per dt) | $ / decatherm	3.02	4.53
Electricity (in MMmwh) | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	$ 3,718	$ 7,100
Liabilities	$ 3,456	$ 2,769
Electricity (in MMmwh) | Level 3 | Forward Contract | Minimum | On-peak
Liabilities
Fixed electric load profile	0.00%	0.00%
Electricity (in MMmwh) | Level 3 | Forward Contract | Minimum | Off-peak
Liabilities
Fixed electric load profile	0.00%	0.00%
Electricity (in MMmwh) | Level 3 | Forward Contract | Maximum | On-peak
Liabilities
Fixed electric load profile	100.00%	100.00%
Electricity (in MMmwh) | Level 3 | Forward Contract | Maximum | Off-peak
Liabilities
Fixed electric load profile	100.00%	100.00%
Electricity (in MMmwh) | Level 3 | Forward Contract | Weighted Average | On-peak
Liabilities
Fixed electric load profile	55.46%	54.55%
Electricity (in MMmwh) | Level 3 | Forward Contract | Weighted Average | Off-peak
Liabilities
Fixed electric load profile	44.54%	45.45%