REGULATION - REGULATORY ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	$ 40,086	$ 30,118
Regulatory liability-current	31,090	28,007
Regulatory liabilities-noncurrent	185,634	193,051
NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	40,086	29,701
Regulatory assets-noncurrent	495,300	519,600
Regulatory liability-current	25,779	28,007
Regulatory liabilities-noncurrent	185,634	191,888
Adelphia
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	0	417
Regulatory assets-noncurrent	5,366	2,499
Regulatory liability-current	5,311	0
Regulatory liabilities-noncurrent	0	1,163
Overrecovered natural gas costs | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory liability-current	17,807	5,510
Derivatives at fair value, net | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory liability-current	7,972	22,497
Regulatory liabilities-noncurrent	116	1,166
Tax Act impact | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities-noncurrent	185,367	190,386
Other noncurrent regulatory liabilities | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities-noncurrent	151	336
New Jersey Clean Energy Program | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	15,697	16,308
Conservation Incentive Program | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	23,099	11,839
Other current regulatory assets | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-current	1,290	1,554
Regulatory assets-noncurrent	45,828	32,695
Expended, net of recoveries | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	66,149	58,483
Liability for future expenditures | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	127,070	135,012
Deferred income taxes | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	40,520	39,694
SAVEGREEN | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	52,690	32,941
Postemployment and other benefit costs | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	56,021	117,194
Deferred storm damage costs | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	2,172	4,343
Cost of removal | NJNG
Schedule of Regulatory Assets And Liabilities [Line Items]
Regulatory assets-noncurrent	$ 104,850	$ 99,238