DEBT - NJR AND NJNG LONG-TERM DEBT (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 28, 2023	Oct. 24, 2022	Sep. 30, 2022
NJR | Unsecured Senior Notes 6.14%, Maturing In 2032
Debt Instrument [Line Items]
Long-term debt			$ 50,000	$ 0
Stated interest rate			6.14%
NJNG
Debt Instrument [Line Items]
NJBPU dividend restriction, equity to capitalization ratio	54.40%
NJNG | Minimum
Debt Instrument [Line Items]
NJBPU dividend restriction, equity to capitalization ratio	30.00%
NJNG | First Mortgage Bonds
Debt Instrument [Line Items]
Maximum amount that can be issued	$ 1,400,000
NJNG | Senior Notes
Debt Instrument [Line Items]
Face amount		$ 100,000
NJNG | Senior Notes | Unsecured Senior Notes 5.47%
Debt Instrument [Line Items]
Stated interest rate			5.47%
Face amount			$ 125,000
NJNG | Senior Notes | Unsecured Senior Notes 5.56%
Debt Instrument [Line Items]
Stated interest rate		5.56%
Face amount		$ 50,000
NJNG | Senior Notes | Unsecured Senior Notes 5.58%
Debt Instrument [Line Items]
Stated interest rate		5.85%
Face amount		$ 50,000