REGULATION - REGULATORY ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	$ 48,898	$ 73,070
Regulatory assets-noncurrent	672,518	609,192
Regulatory liability-current	12,884	32,981
Regulatory liabilities-noncurrent	171,177	175,847
Expended, net of recoveries
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	75,000
NJNG
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	48,898	73,070
Regulatory assets-noncurrent	667,308	604,097
Regulatory liability-current	10,643	32,457
Regulatory liabilities-noncurrent	171,177	175,847
NJNG \| Overrecovered natural gas costs
Regulatory Assets and Liabilities [Line Items]
Regulatory liability-current	10,643	32,457
NJNG \| Tax Act impact
Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities-noncurrent	170,309	175,328
NJNG \| Other noncurrent regulatory liabilities
Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities-noncurrent	868	115
NJNG \| Derivatives at fair value, net
Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities-noncurrent	0	404
NJNG \| New Jersey Clean Energy Program
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	17,171	18,491
NJNG \| Conservation Incentive Program
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	22,697	51,442
NJNG \| Derivatives at fair value, net
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	7,544	1,363
NJNG \| Other current regulatory assets
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-current	1,486	1,774
Regulatory assets-noncurrent	63,612	59,924
NJNG \| Expended, net of recoveries
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	74,961	77,475
NJNG \| Liability for future expenditures
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	166,990	161,650
NJNG \| Deferred income taxes
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	46,013	42,595
NJNG \| SAVEGREEN
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	141,562	107,796
NJNG \| Postemployment and other benefit costs
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	41,275	23,772
NJNG \| Cost of removal
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	132,895	130,885
Adelphia
Regulatory Assets and Liabilities [Line Items]
Regulatory assets-noncurrent	5,210	5,095
Regulatory liability-current	$ 2,241	$ 524

NEW JERSEY RESOURCES CORP 10-K