PENSION AND OTHER POSTRETIREMENT BENEFITS - DETAILS OF ACTIVITY WITHIN THE REGULATORY ASSET AND ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Regulatory Assets
Beginning balance	$ 72,529	$ 61,584
Amounts arising during the period: net actuarial (loss) gain	(19,155)	17,377
Amounts arising during the period: prior service credit (cost)		0
Amounts amortized to net periodic costs: net actuarial loss	(6,187)	(6,337)
Amounts amortized to net periodic costs: prior service cost	(88)	(95)
Ending balance	47,099	72,529
Accumulated Other Comprehensive Loss  (pre-tax)
Beginning balance	57,489	51,285
Amounts arising during the period: net actuarial (loss) gain	(7,465)	11,459
Amounts arising during the period: prior service credit (cost)		0
Amounts amortized to net periodic costs: net actuarial loss	(6,740)	(5,244)
Amortization to net periodic costs: prior service (credits) costs	(10)	(11)
Ending balance	43,274	57,489
Other Postretirement Benefits
Regulatory Assets
Beginning balance	13,363	12,251
Amounts arising during the period: net actuarial (loss) gain	(11,763)	1,718
Amounts arising during the period: prior service credit (cost)		(436)
Amounts amortized to net periodic costs: net actuarial loss	(884)	(672)
Amounts amortized to net periodic costs: prior service cost	502	502
Ending balance	1,218	13,363
Accumulated Other Comprehensive Loss  (pre-tax)
Beginning balance	2,768	964
Amounts arising during the period: net actuarial (loss) gain	(1,540)	2,194
Amounts arising during the period: prior service credit (cost)		(317)
Amounts amortized to net periodic costs: net actuarial loss	(233)	(180)
Amortization to net periodic costs: prior service (credits) costs	107	107
Ending balance	1,102	2,768
South Jersey Gas Company | Pension Benefits
Regulatory Assets
Beginning balance	65,676	60,668
Amounts arising during the period: net actuarial (loss) gain	(14,357)	10,595
Amounts arising during the period: prior service credit (cost)		0
Amounts arising during the period: other (curtailments, settlements, special termination)	0
Amounts amortized to net periodic costs: net actuarial loss	(6,144)	(5,492)
Amounts amortized to net periodic costs: prior service cost	(88)	(95)
Ending balance	45,087	65,676
Accumulated Other Comprehensive Loss  (pre-tax)
Beginning balance	47,437	42,190
Amounts arising during the period: net actuarial (loss) gain	(3,350)	9,119
Amounts arising during the period: prior service credit (cost)		0
Amounts arising during the period: other (curtailments, settlements, special termination)	(3,177)
Amounts amortized to net periodic costs: net actuarial loss	(5,423)	(3,872)
Amortization to net periodic costs: prior service (credits) costs	0	0
Ending balance	35,487	47,437
South Jersey Gas Company | Other Postretirement Benefits
Regulatory Assets
Beginning balance	11,750	11,342
Amounts arising during the period: net actuarial (loss) gain	(8,951)	1,014
Amounts arising during the period: prior service credit (cost)		(436)
Amounts arising during the period: other (curtailments, settlements, special termination)	0
Amounts amortized to net periodic costs: net actuarial loss	(884)	(672)
Amounts amortized to net periodic costs: prior service cost	502	502
Ending balance	2,417	11,750
Accumulated Other Comprehensive Loss  (pre-tax)
Beginning balance	0	0
Amounts arising during the period: net actuarial (loss) gain	0	0
Amounts arising during the period: prior service credit (cost)		0
Amounts arising during the period: other (curtailments, settlements, special termination)	0
Amounts amortized to net periodic costs: net actuarial loss	0	0
Amortization to net periodic costs: prior service (credits) costs	0	0
Ending balance	$ 0	$ 0