DEBT - NJR AND NJNG LONG-TERM DEBT (Details) - USD ($) $ in Millions	Apr. 15, 2025	Sep. 30, 2025	Aug. 21, 2025	Nov. 07, 2024
NJNG
Debt Instrument [Line Items]
NJBPU dividend restriction, equity to capitalization ratio		54.10%
Minimum | NJNG
Debt Instrument [Line Items]
NJBPU dividend restriction, equity to capitalization ratio		30.00%
Senior Notes | NJNG
Debt Instrument [Line Items]
Note purchase agreement amount			$ 200
Face amount			$ 200
Senior Notes | Unsecured Senior Notes 5.55% | NJR
Debt Instrument [Line Items]
Stated interest rate				5.55%
Note purchase agreement amount				$ 100
Face amount				$ 100
Senior Notes | Unsecured Senior Notes 2.82% | NJNG
Debt Instrument [Line Items]
Stated interest rate	2.82%
Interest rate terms	10-year
Debt instrument repaid principal	$ 50
Senior Notes | Unsecured Senior Notes 5.16% | NJNG
Debt Instrument [Line Items]
Stated interest rate			5.16%
Note purchase agreement amount			$ 100
Face amount			$ 100
Senior Notes | Unsecured Senior Notes 5.58% | NJNG
Debt Instrument [Line Items]
Stated interest rate			5.85%
Note purchase agreement amount			$ 100
Face amount			$ 100
First Mortgage Bonds | NJNG
Debt Instrument [Line Items]
Maximum amount that can be issued		$ 1,500