REGULATORY ASSETS AND REGULATORY LIABILITIES - Regulatory Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
ETG
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 193,081	$ 189,671
ETG | Environmental Remediation Costs, Expended - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	24,268	13,972
ETG | Liability for Future Expenditures
Regulatory Assets [Line Items]
Total Regulatory Assets	75,443	77,830
ETG | Deferred ARO Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	37,910	33,872
ETG | Deferred Pension and Other Postretirement Benefit Costs - Unrecognized Prior Service Cost
Regulatory Assets [Line Items]
Total Regulatory Assets	28,438	30,881
ETG | Deferred Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	611	813
ETG | Deferred Gas Costs - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
ETG | CIP Receivable
Regulatory Assets [Line Items]
Total Regulatory Assets	3,884	2,955
ETG | SBC Receivable (excluding RAC)
Regulatory Assets [Line Items]
Total Regulatory Assets	551	0
ETG | Deferred Interest Rate Contracts
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
ETG | EET/EEP
Regulatory Assets [Line Items]
Total Regulatory Assets	7,657	5,199
ETG | AFUDC - Equity Related Deferrals
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
ETG | WNC
Regulatory Assets [Line Items]
Total Regulatory Assets		4,269
ETG | Deferred COVID-19 Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	11,625	10,225
ETG | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	2,694	9,655
SJG
Regulatory Assets [Line Items]
Total Regulatory Assets	453,268	482,745
SJG | Environmental Remediation Costs, Expended - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	150,189	151,630
SJG | Liability for Future Expenditures
Regulatory Assets [Line Items]
Total Regulatory Assets	97,492	97,964
SJG | Deferred ARO Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	52,395	47,784
SJG | Deferred Pension and Other Postretirement Benefit Costs - Unrecognized Prior Service Cost
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
SJG | Deferred Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	47,504	47,504
SJG | Deferred Gas Costs - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	16,217	38,234
SJG | CIP Receivable
Regulatory Assets [Line Items]
Total Regulatory Assets	11,053	17,776
SJG | SBC Receivable (excluding RAC)
Regulatory Assets [Line Items]
Total Regulatory Assets	7,308	7,519
SJG | Deferred Interest Rate Contracts
Regulatory Assets [Line Items]
Total Regulatory Assets	2,861	8,002
SJG | EET/EEP
Regulatory Assets [Line Items]
Total Regulatory Assets	24,464	20,632
SJG | AFUDC - Equity Related Deferrals
Regulatory Assets [Line Items]
Total Regulatory Assets	12,675	12,199
SJG | WNC
Regulatory Assets [Line Items]
Total Regulatory Assets		0
SJG | Deferred COVID-19 Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	7,791	7,687
SJG | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	23,319	25,814
SJI
Regulatory Assets [Line Items]
Total Regulatory Assets	646,349	672,416
SJI | Environmental Remediation Costs, Expended - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	174,457	165,602
SJI | Liability for Future Expenditures
Regulatory Assets [Line Items]
Total Regulatory Assets	172,935	175,794
SJI | Deferred ARO Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	90,305	81,656
SJI | Deferred Pension and Other Postretirement Benefit Costs - Unrecognized Prior Service Cost
Regulatory Assets [Line Items]
Total Regulatory Assets	28,438	30,881
SJI | Deferred Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	48,115	48,317
SJI | Deferred Gas Costs - Net
Regulatory Assets [Line Items]
Total Regulatory Assets	16,217	38,234
SJI | CIP Receivable
Regulatory Assets [Line Items]
Total Regulatory Assets	14,937	20,731
SJI | SBC Receivable (excluding RAC)
Regulatory Assets [Line Items]
Total Regulatory Assets	7,859	7,519
SJI | Deferred Interest Rate Contracts
Regulatory Assets [Line Items]
Total Regulatory Assets	2,861	8,002
SJI | EET/EEP
Regulatory Assets [Line Items]
Total Regulatory Assets	32,121	25,831
SJI | AFUDC - Equity Related Deferrals
Regulatory Assets [Line Items]
Total Regulatory Assets	12,675	12,199
SJI | WNC
Regulatory Assets [Line Items]
Total Regulatory Assets		4,269
SJI | Deferred COVID-19 Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	19,416	17,912
SJI | Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 26,013	$ 35,469