REGULATION - ADDITIONAL INFORMATION (Details) - USD ($) $ in Thousands				6 Months Ended
	Apr. 12, 2023	Mar. 30, 2023	Feb. 22, 2023	Mar. 31, 2023	Sep. 30, 2022
Schedule of Regulatory Filings [Line Items]
Regulatory assets				$ 501,829	$ 500,666
NJNG
Schedule of Regulatory Filings [Line Items]
Regulatory assets				$ 3,900	$ 6,900
Interim rate increase (decrease), amount			$ (32,500)
Approved rate increase (decrease), amount		$ 31,400
Base Rate Stipulation
Schedule of Regulatory Filings [Line Items]
Weighted average cost of capital				6.84%
Approved return on equity				9.60%
BGSS | NJNG | Subsequent Event
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount	$ 81,900
BGSS | NJNG
Schedule of Regulatory Filings [Line Items]
Interim rate increase (decrease), amount			$ (29,900)
BPU | NJNG
Schedule of Regulatory Filings [Line Items]
Approved rate increase (decrease), amount		$ 3,500
BGSS Balancing | NJNG | Subsequent Event
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount	9,000
Conservation Incentive Program | NJNG | Subsequent Event
Schedule of Regulatory Filings [Line Items]
Requested rate increase (decrease), amount	10,200
RAC | Subsequent Event
Schedule of Regulatory Filings [Line Items]
Interim rate increase (decrease), amount	3,700
NJCEP | Subsequent Event
Schedule of Regulatory Filings [Line Items]
Interim rate increase (decrease), amount	$ (900)