DERIVATIVE INSTRUMENTS - OFFSETTING ARRANGEMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commodity contract
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets/liabilities	$ 60,135	$ 61,190
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	60,135	61,190
Gross amounts not offset in the balance sheet, Financial Instruments	(32,185)	(21,045)
Gross amounts not offset in the balance sheet, Cash Collateral Posted	0	(7,252)
Net amount	27,950	32,893
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized assets/liabilities	(50,171)	(31,390)
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	(50,171)	(31,390)
Gross amounts not offset in the balance sheet, Financial Instruments	32,185	21,045
Gross amounts not offset in the balance sheet, Cash Collateral Posted	12,878	0
Net amount	(5,108)	(10,345)
Other Contract
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized assets/liabilities	(12,660)	(7,873)
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	(12,660)	(7,873)
Gross amounts not offset in the balance sheet, Financial Instruments	0	0
Gross amounts not offset in the balance sheet, Cash Collateral Posted	0	0
Net amount	(12,660)	(7,873)
South Jersey Gas Company \| Commodity contract
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets/liabilities	16,909	5,479
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	16,909	5,479
Gross amounts not offset in the balance sheet, Financial Instruments	(11,860)	(347)
Gross amounts not offset in the balance sheet, Cash Collateral Posted	0	688
Net amount	5,049	5,820
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized assets/liabilities	(14,766)	(2,189)
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	(14,766)	(2,189)
Gross amounts not offset in the balance sheet, Financial Instruments	11,860	347
Gross amounts not offset in the balance sheet, Cash Collateral Posted	2,706	0
Net amount	(200)	(1,842)
South Jersey Gas Company \| Other Contract
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized assets/liabilities	(7,856)	(5,867)
Gross amount offset in the balance sheet	0	0
Net amounts of assets/liabilities in balance sheet	(7,856)	(5,867)
Gross amounts not offset in the balance sheet, Financial Instruments	0	0
Gross amounts not offset in the balance sheet, Cash Collateral Posted	0	0
Net amount	$ (7,856)	$ (5,867)

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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