REGULATORY ASSETS & REGULATORY LIABILITIES - LIABILITIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
South Jersey Gas Company
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 274,482	$ 286,539
Regulatory liabilities	274,482	286,539
Regulatory assets	496,177	492,365
South Jersey Gas Company | Excess Plant Removal Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	16,333	20,805
Regulatory liabilities	16,333	20,805
South Jersey Gas Company | Excess Deferred Taxes
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	251,355	259,863
Regulatory liabilities	251,355	259,863
South Jersey Gas Company | Deferred Revenues - Net
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
South Jersey Gas Company | CIP Payable
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	6,794	5,871
Regulatory liabilities	6,794	5,871
South Jersey Gas Company | Amounts to be Refunded to Customers
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
South Jersey Gas Company | WNC
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0
Regulatory liabilities	0
South Jersey Gas Company | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
South Jersey Gas Company | Unprotected Excess Deferred Income Tax
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	26,100
Regulatory liabilities	$ 26,100
Refund period	5 years
SJI
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 442,918	478,499
Regulatory liabilities	442,918	478,499
Regulatory assets	665,932	662,969
SJI | Excess Plant Removal Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	52,676	70,107
Regulatory liabilities	52,676	70,107
SJI | Excess Deferred Taxes
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	369,050	379,851
Regulatory liabilities	369,050	379,851
SJI | Deferred Revenues - Net
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	52	3,188
Regulatory liabilities	52	3,188
SJI | CIP Payable
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	6,794	5,871
Regulatory liabilities	6,794	5,871
SJI | Amounts to be Refunded to Customers
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	10,625	17,039
Regulatory liabilities	10,625	17,039
SJI | WNC
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,684
Regulatory liabilities	2,684
SJI | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,037	2,443
Regulatory liabilities	1,037	2,443
ETG Utility Operations
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	168,436	189,336
Regulatory liabilities	168,436	189,336
Regulatory assets	169,231	169,921
ETG Utility Operations | Excess Plant Removal Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	36,343	47,909
Regulatory liabilities	36,343	47,909
ETG Utility Operations | Excess Deferred Taxes
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	117,695	118,757
Regulatory liabilities	117,695	118,757
ETG Utility Operations | Deferred Revenues - Net
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	52	3,188
Regulatory liabilities	52	3,188
ETG Utility Operations | CIP Payable
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
ETG Utility Operations | Amounts to be Refunded to Customers
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	10,625	17,039
Regulatory liabilities	10,625	17,039
ETG Utility Operations | WNC
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,684
Regulatory liabilities	2,684
ETG Utility Operations | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,037	2,443
Regulatory liabilities	1,037	2,443
ELK Utility Operations
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	2,624
Regulatory liabilities	0	2,624
Regulatory assets	524	683
ELK Utility Operations | Excess Plant Removal Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	1,393
Regulatory liabilities	0	1,393
ELK Utility Operations | Excess Deferred Taxes
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	1,231
Regulatory liabilities	0	1,231
ELK Utility Operations | Deferred Revenues - Net
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
ELK Utility Operations | CIP Payable
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
ELK Utility Operations | Amounts to be Refunded to Customers
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	0	0
ELK Utility Operations | WNC
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0
Regulatory liabilities	0
ELK Utility Operations | Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
Regulatory liabilities	$ 0	$ 0