DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Oct. 24, 2022	Sep. 30, 2022
Debt Instrument [Line Items]
Meter financing obligation	$ 22,875		$ 23,752
Total long-term debt	2,768,017		2,485,402
NJNG
Debt Instrument [Line Items]
Less: Debt issuance costs	(9,770)		(9,528)
Less: Current maturities of long-term debt	(78,477)		(6,538)
Total long-term debt	1,410,950		1,307,069
NJNG | Meter financing obligation
Debt Instrument [Line Items]
Meter financing obligation	$ 31,352		30,290
NJNG | First Mortgage Bonds | Series OO
Debt Instrument [Line Items]
Stated interest rate	3.00%
Long-term debt	$ 46,500		46,500
NJNG | First Mortgage Bonds | Series PP
Debt Instrument [Line Items]
Stated interest rate	3.15%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series QQ
Debt Instrument [Line Items]
Stated interest rate	3.58%
Long-term debt	$ 70,000		70,000
NJNG | First Mortgage Bonds | Series RR
Debt Instrument [Line Items]
Stated interest rate	4.61%
Long-term debt	$ 55,000		55,000
NJNG | First Mortgage Bonds | Series SS
Debt Instrument [Line Items]
Stated interest rate	2.82%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series TT
Debt Instrument [Line Items]
Stated interest rate	3.66%
Long-term debt	$ 100,000		100,000
NJNG | First Mortgage Bonds | Series UU
Debt Instrument [Line Items]
Stated interest rate	3.63%
Long-term debt	$ 125,000		125,000
NJNG | First Mortgage Bonds | Series VV
Debt Instrument [Line Items]
Stated interest rate	4.01%
Long-term debt	$ 125,000		125,000
NJNG | First Mortgage Bonds | Series WW
Debt Instrument [Line Items]
Stated interest rate	3.50%
Long-term debt	$ 10,300		10,300
NJNG | First Mortgage Bonds | Series XX
Debt Instrument [Line Items]
Stated interest rate	3.38%
Long-term debt	$ 10,500		10,500
NJNG | First Mortgage Bonds | Series YY
Debt Instrument [Line Items]
Stated interest rate	2.45%
Long-term debt	$ 15,000		15,000
NJNG | First Mortgage Bonds | Series ZZ
Debt Instrument [Line Items]
Stated interest rate	3.76%
Long-term debt	$ 100,000		100,000
NJNG | First Mortgage Bonds | Series AAA
Debt Instrument [Line Items]
Stated interest rate	3.86%
Long-term debt	$ 85,000		85,000
NJNG | First Mortgage Bonds | Series BBB
Debt Instrument [Line Items]
Stated interest rate	2.75%
Long-term debt	$ 9,545		9,545
NJNG | First Mortgage Bonds | Series CCC
Debt Instrument [Line Items]
Stated interest rate	3.00%
Long-term debt	$ 41,000		41,000
NJNG | First Mortgage Bonds | Series DDD
Debt Instrument [Line Items]
Stated interest rate	3.13%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series EEE
Debt Instrument [Line Items]
Stated interest rate	3.13%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series FFF
Debt Instrument [Line Items]
Stated interest rate	3.33%
Long-term debt	$ 25,000		25,000
NJNG | First Mortgage Bonds | Series GGG
Debt Instrument [Line Items]
Stated interest rate	2.87%
Long-term debt	$ 25,000		25,000
NJNG | First Mortgage Bonds | Series HHH
Debt Instrument [Line Items]
Stated interest rate	2.97%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series III
Debt Instrument [Line Items]
Stated interest rate	2.97%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series JJJ
Debt Instrument [Line Items]
Stated interest rate	3.07%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series LLL
Debt Instrument [Line Items]
Stated interest rate	4.37%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series MMM
Debt Instrument [Line Items]
Stated interest rate	4.71%
Long-term debt	$ 50,000		50,000
NJNG | First Mortgage Bonds | Series NNN
Debt Instrument [Line Items]
Stated interest rate	5.47%
Long-term debt	$ 125,000		0
NJNG | First Mortgage Bonds | Series OOO
Debt Instrument [Line Items]
Stated interest rate	5.56%
Long-term debt	$ 50,000		0
NJR
Debt Instrument [Line Items]
Less: Debt issuance costs	(3,656)		(3,753)
Less: Current maturities of long-term debt	0		(50,000)
Total long-term debt	$ 1,116,344		1,066,247
NJR | Unsecured senior notes 3.20%
Debt Instrument [Line Items]
Stated interest rate	3.20%
Long-term debt	$ 0		50,000
NJR | Unsecured senior notes 3.48%
Debt Instrument [Line Items]
Stated interest rate	3.48%
Long-term debt	$ 100,000		100,000
NJR | Unsecured senior notes 3.54%
Debt Instrument [Line Items]
Stated interest rate	3.54%
Long-term debt	$ 100,000		100,000
NJR | Unsecured senior notes 3.96%
Debt Instrument [Line Items]
Stated interest rate	3.96%
Long-term debt	$ 100,000		100,000
NJR | Unsecured senior notes 3.29%
Debt Instrument [Line Items]
Stated interest rate	3.29%
Long-term debt	$ 150,000		150,000
NJR | Unsecured senior note 3.60%
Debt Instrument [Line Items]
Stated interest rate	3.60%
Long-term debt	$ 130,000		130,000
NJR | Unsecured senior note 3.50%
Debt Instrument [Line Items]
Stated interest rate	3.50%
Long-term debt	$ 130,000		130,000
NJR | Unsecured senior notes 3.25%
Debt Instrument [Line Items]
Stated interest rate	3.25%
Long-term debt	$ 80,000		80,000
NJR | Unsecured senior note 3.13%
Debt Instrument [Line Items]
Stated interest rate	3.13%
Long-term debt	$ 120,000		120,000
NJR | Unsecured Senior Notes 4.38%
Debt Instrument [Line Items]
Stated interest rate	4.38%
Long-term debt	$ 110,000		110,000
NJR | Unsecured Senior Notes 3.64%
Debt Instrument [Line Items]
Stated interest rate	3.64%
Long-term debt	$ 50,000		50,000
NJR | Unsecured Senior Notes 6.14%, Maturing In 2032
Debt Instrument [Line Items]
Stated interest rate		6.14%
Long-term debt		$ 50,000	0
CEV
Debt Instrument [Line Items]
Long-term debt	278,401		130,618
Less: Current maturities of long-term debt	(37,678)		(18,532)
Total CEV long-term debt	$ 240,723		$ 112,086