REGULATION - ADDITIONAL INFORMATION (Details) $ in Thousands										1 Months Ended											2 Months Ended	3 Months Ended	12 Months Ended
	Sep. 27, 2023 USD ($)	Sep. 18, 2023 USD ($)	Sep. 11, 2023 USD ($)	Jul. 28, 2023 USD ($)	Jun. 28, 2023 USD ($)	Jun. 01, 2023 USD ($)	Apr. 12, 2023 USD ($)	Mar. 30, 2023 USD ($)	Feb. 22, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jul. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jan. 31, 2022 USD ($)	Nov. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Apr. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)	May 31, 2020 USD ($)	Feb. 28, 2019 USD ($) projectComponent	Jan. 31, 2021 USD ($)	May 31, 2023 USD ($)	Sep. 30, 2023 USD ($) project filing
Schedule of Regulatory Filings [Line Items]
Regulatory assets										$ 500,666													$ 584,830
Number of interim filings during each fiscal year | filing																							2
Number of days notice for refund																							5 days
NJNG
Schedule of Regulatory Filings [Line Items]
Regulatory assets										495,300													$ 579,599
Interim rate increase (decrease), amount				$ 28,200
Approved rate increase (decrease), amount								$ 31,400			$ 28,900
NJNG | COVID-19 Pandemic
Schedule of Regulatory Filings [Line Items]
Regulatory assets										6,900													$ 3,900
Environmental Remediation Costs
Schedule of Regulatory Filings [Line Items]
Regulatory assets, amortization period																							7 years
Postemployment and Other Benefit Costs
Schedule of Regulatory Filings [Line Items]
Regulatory assets, amortization period																							7 years
Deferred Storm Damage Costs
Schedule of Regulatory Filings [Line Items]
Regulatory assets, amortization period																							7 years
Base Rate Stipulation
Schedule of Regulatory Filings [Line Items]
Weighted average cost of capital																							6.84%
Approved return on equity																							9.60%
Approved equity capital structure, percentage																							54.00%
Public utilities, approved depreciation rate, percentage																							2.78%
SAVEGREEN
Schedule of Regulatory Filings [Line Items]
Public utility extension term																	3 years
Capital investments approved by the BPU																	$ 126,100
Financing options																	109,400
Operations and maintenance expense																	23,400
Annual recovery increase	$ 9,000					$ 10,700							$ 2,200
SAVEGREEN | Minimum
Schedule of Regulatory Filings [Line Items]
Regulatory assets, amortization period																							2 years
Program recovery term																							3 years
SAVEGREEN | Maximum
Schedule of Regulatory Filings [Line Items]
Regulatory assets, amortization period																							10 years
Program recovery term																							10 years
BPU | NJNG
Schedule of Regulatory Filings [Line Items]
Annual recovery increase					$ 700
Approved rate increase (decrease), amount	$ 3,200									3,200
BPU | NJNG
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount														$ 79,000
BGSS | NJNG
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount														24,200
Interim rate increase (decrease), amount									$ (29,900)												$ (20,600)	$ (32,400)
Interim rate increase (decrease), amount, net of tax																					$ (19,300)
BGSS | NJNG
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount						(38,600)				81,900				2,900
BGSS Balancing | NJNG
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount						(7,400)				9,000				13,000
Conservation Incentive Program | NJNG
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount		$ 27,000				$ 27,500				10,200				(6,300)
NJNG EE Recovery Rate | NJNG
Schedule of Regulatory Filings [Line Items]
Annual recovery increase										(3,500)
Approved rate increase (decrease), amount																			$ 11,400
RAC
Schedule of Regulatory Filings [Line Items]
Approved rate increase (decrease), amount			$ 2,400				$ 3,700			3,800		$ 600				$ 1,300
NJCEP
Schedule of Regulatory Filings [Line Items]
Approved rate increase (decrease), amount			$ 5,000				$ (900)			2,200		$ (2,900)				$ 6,000
USF
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount										$ (1,600)					$ 4,900
SAFE Program
Schedule of Regulatory Filings [Line Items]
Capital investments approved by the BPU																							$ 130,000
Capital investments approved by the BPU, period																							4 years
Capital investments to be recovered approved by the Board of Public Utilities																							$ 200,000
Recovery amount																							$ 157,500
SAFE II
Schedule of Regulatory Filings [Line Items]
Capital investments approved by the BPU, period																							5 years
NJ RISE Program
Schedule of Regulatory Filings [Line Items]
Approved return on equity																							9.75%
Program recovery term																							5 years
Number of capital investment projects | project																							6
Originally filed petition for capital investments to Board of Public Utilities																							$ 102,500
NJ RISE Program | Minimum
Schedule of Regulatory Filings [Line Items]
Approved equity capital structure, percentage																							6.74%
NJ RISE Program | Maximum
Schedule of Regulatory Filings [Line Items]
Approved equity capital structure, percentage																							6.90%
NJ RISE And SAFE II Capital Investments | NJNG
Schedule of Regulatory Filings [Line Items]
Capital investment costs																	$ 3,400
SAFE II and NJ RISE
Schedule of Regulatory Filings [Line Items]
Approved rate increase (decrease), amount														$ 300
Infrastructure Investment Program (IIP) | NJNG
Schedule of Regulatory Filings [Line Items]
Program recovery term																		5 years		5 years
Number of project components | projectComponent																				2
Public utilities, investments																		$ 150,000		$ 507,000