LEASES - Lease Maturity and Balance Sheet Information (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020 (excluding the nine months ended September 30, 2020)	$ 206,000
2021	534,000
2022	348,000
2023	190,000
2024	165,000
Thereafter	235,000
Total lease payments	1,678,000
Less imputed interest	109,000
Total lease liabilities	1,569,000	$ 1,900,000
Finance Lease, Liability, Payment, Due [Abstract]
2020 (excluding the nine months ended September 30, 2020)	36,000
2021	145,000
2022	145,000
2023	145,000
2024	145,000
Thereafter	6,557,000
Total lease payments	7,173,000
Less imputed interest	4,122,000
Total lease liabilities	3,051,000
Operating Lease, Liability [Abstract]
Current lease liabilities (included in Other Current Liabilities)	581,000
Long-term lease liabilities (included in Other Noncurrent Liabilities)	988,000
Finance Lease Liability [Abstract]
Current lease liabilities (included in Other Current Liabilities)	0
Long-term lease liabilities (included in Other Noncurrent Liabilities)	$ 3,051,000
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
SJG
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020 (excluding the nine months ended September 30, 2020)	$ 23,000
2021	39,000
2022	21,000
2023	19,000
2024	12,000
Thereafter	102,000
Total lease payments	216,000
Less imputed interest	28,000
Total lease liabilities	188,000
Finance Lease, Liability, Payment, Due [Abstract]
Total lease liabilities	0
Operating Lease, Liability [Abstract]
Current lease liabilities (included in Other Current Liabilities)	49,000
Long-term lease liabilities (included in Other Noncurrent Liabilities)	$ 139,000