v3.26.1
DERIVATIVE INSTRUMENTS - INCOME STATEMENT RELATED DISCLOSURES (Details) - Not Designated as Hedging Instrument - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives $ 2,386 $ (14,816) $ 1,321 $ 13,667
ES | Physical commodity contracts | Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]     Natural gas purchases Natural gas purchases
Amount of gain (loss) recognized in income on derivatives (838) (158) $ 109 $ (1,185)
ES | Physical commodity contracts | Location, Statement of Income, Balance [Axis]: us-gaap:OtherCostAndExpenseOperating        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives 94 1,356 $ 127 $ 230
ES | Physical commodity contracts | Location, Statement of Income, Balance [Axis]: us-gaap:RegulatedAndUnregulatedOperatingRevenue        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]     Nonutility Nonutility
Amount of gain (loss) recognized in income on derivatives 1,092 (24,938) $ (498) $ 8,510
ES | Financial commodity contracts        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives 2,038 8,924 1,583 6,112
NJNG        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives (370) (20,135) (17,619) (2,732)
NJNG | Physical commodity contracts        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives 655 1,166 (2,390) (17,408)
NJNG | Financial commodity contracts        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of gain (loss) recognized in income on derivatives $ (1,025) $ (21,301) $ (15,229) $ 14,676