DEBT - NJNG SHORT-TERM DEBT (Details) - NJNG	12 Months Ended
	Sep. 30, 2021 USD ($) lease	Sep. 30, 2022 USD ($) debtInstrument
Letter of Credit
Line of Credit Facility [Line Items]
Number of debt instruments (in debt instruments) | debtInstrument		2
Letters of credit outstanding, amount	$ 731,000	$ 731,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Number of mutual options | lease	2
Number of mutual options, extension period	1 year
Line of credit facility, maximum borrowing capacity, incremental increase	$ 50,000,000
Line of credit facility, maximum borrowing capacity, maximum increase	100,000,000
Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	30,000,000
Committed Credit Facilities Due September 2026 | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000