FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / decatherm	Dec. 31, 2019 USD ($) $ / decatherm
Assets
Available-for-Sale Securities	$ 32	$ 40
Changes in significant unobservable inputs [Roll forward]
Balance at beginning of period	17,574	16,061
Other changes in fair value from continuing and new contracts, net	11,078	19,688
Settlements	(17,646)	(18,175)
Balance at end of period	11,006	17,574
Measurement at fair value on recurring basis
Assets
Available-for-Sale Securities	32	40
Derivatives - Energy Related Assets	48,374	60,135
Assets	48,406	60,175
Liabilities
Derivatives - Energy Related Liabilities	31,953	50,171
Derivatives - Other	9,938	12,660
Liabilities	41,891	62,831
Measurement at fair value on recurring basis | Level 1
Assets
Available-for-Sale Securities	32	40
Derivatives - Energy Related Assets	11,447	16,931
Assets	11,479	16,971
Liabilities
Derivatives - Energy Related Liabilities	8,605	34,446
Derivatives - Other	0	0
Liabilities	8,605	34,446
Measurement at fair value on recurring basis | Level 2
Assets
Available-for-Sale Securities	0	0
Derivatives - Energy Related Assets	23,527	17,841
Assets	23,527	17,841
Liabilities
Derivatives - Energy Related Liabilities	20,954	7,936
Derivatives - Other	9,938	12,660
Liabilities	30,892	20,596
Measurement at fair value on recurring basis | Level 3
Assets
Available-for-Sale Securities	0	0
Derivatives - Energy Related Assets	13,400	25,363
Assets	13,400	25,363
Liabilities
Derivatives - Energy Related Liabilities	2,394	7,789
Derivatives - Other	0	0
Liabilities	2,394	7,789
Natural Gas (in MMdts) | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	12,824	21,645
Liabilities	$ 1,764	$ 4,333
Natural Gas (in MMdts) | Level 3 | Forward Contract | Minimum | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	1.44	1.57
Natural Gas (in MMdts) | Level 3 | Forward Contract | Maximum | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	6.77	7.28
Natural Gas (in MMdts) | Level 3 | Forward Contract | Weighted Average | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	2.67	2.38
Electricity (in MMmwh) | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	$ 576	$ 3,718
Liabilities	$ 630	$ 3,456
Electricity (in MMmwh) | Level 3 | Forward Contract | Minimum | Discounted Cash Flow | Fixed electric load profile (on-peak)
Liabilities
Derivative, measurement input	0.4034	0.0000
Electricity (in MMmwh) | Level 3 | Forward Contract | Minimum | Discounted Cash Flow | Fixed electric load profile (off-peak)
Liabilities
Derivative, measurement input	0.0000	0.0000
Electricity (in MMmwh) | Level 3 | Forward Contract | Maximum | Discounted Cash Flow | Fixed electric load profile (on-peak)
Liabilities
Derivative, measurement input	1.0000	1.0000
Electricity (in MMmwh) | Level 3 | Forward Contract | Maximum | Discounted Cash Flow | Fixed electric load profile (off-peak)
Liabilities
Derivative, measurement input	0.5966	1.0000
Electricity (in MMmwh) | Level 3 | Forward Contract | Weighted Average | Discounted Cash Flow | Fixed electric load profile (on-peak)
Liabilities
Derivative, measurement input	0.6569	0.5546
Electricity (in MMmwh) | Level 3 | Forward Contract | Weighted Average | Discounted Cash Flow | Fixed electric load profile (off-peak)
Liabilities
Derivative, measurement input	0.3431	0.4454
South Jersey Gas Company
Changes in significant unobservable inputs [Roll forward]
Balance at beginning of period	$ 5,035	$ 4,928
Other changes in fair value from continuing and new contracts, net	3,385	5,035
Settlements	(5,035)	(4,928)
Balance at end of period	3,385	5,035
South Jersey Gas Company | Measurement at fair value on recurring basis
Assets
Derivatives - Energy Related Assets	4,140	16,909
Assets	4,140	16,909
Liabilities
Derivatives - Energy Related Liabilities	3,058	14,766
Derivatives - Other	9,938	7,856
Liabilities	12,996	22,622
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 1
Assets
Derivatives - Energy Related Assets	715	11,860
Assets	715	11,860
Liabilities
Derivatives - Energy Related Liabilities	2,891	14,565
Derivatives - Other	0	0
Liabilities	2,891	14,565
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 2
Assets
Derivatives - Energy Related Assets	32	0
Assets	32	0
Liabilities
Derivatives - Energy Related Liabilities	159	187
Derivatives - Other	9,938	7,856
Liabilities	10,097	8,043
South Jersey Gas Company | Measurement at fair value on recurring basis | Level 3
Assets
Derivatives - Energy Related Assets	3,393	5,049
Assets	3,393	5,049
Liabilities
Derivatives - Energy Related Liabilities	8	14
Derivatives - Other	0	0
Liabilities	8	14
South Jersey Gas Company | Natural Gas (in MMdts) | Level 3 | Forward Contract | Discounted Cash Flow
Liabilities
Assets	3,393	5,049
Liabilities	$ 8	$ 14
South Jersey Gas Company | Natural Gas (in MMdts) | Level 3 | Forward Contract | Minimum | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	2.48	1.85
South Jersey Gas Company | Natural Gas (in MMdts) | Level 3 | Forward Contract | Maximum | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	3.63	3.61
South Jersey Gas Company | Natural Gas (in MMdts) | Level 3 | Forward Contract | Weighted Average | Discounted Cash Flow | Forward price (per dt)
Liabilities
Derivative, measurement input | $ / decatherm	3.16	3.02