DERIVATIVE INSTRUMENTS - INCOME STATEMENT RELATED DISCLOSURES (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	$ 9,400	$ (12,696)	$ 56,705
Energy Services | Physical commodity contracts | Operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonutility	Nonutility	Nonutility
Amount of gain (loss) recognized in income on derivatives	$ (8,569)	$ 30,011	$ 1,163
Energy Services | Physical commodity contracts | Natural gas purchases
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gas purchases - Utility and Nonutility	Gas purchases - Utility and Nonutility	Gas purchases - Utility and Nonutility
Amount of gain (loss) recognized in income on derivatives	$ 3,580	$ 1,052	$ (3,366)
Energy Services | Financial commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	14,403	(43,997)	58,949
Energy Services | Foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	(14)	238	(41)
Natural Gas Distribution
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	39,984	34,899	(1,826)
Natural Gas Distribution | Physical commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	7,116	2,174	2,077
Natural Gas Distribution | Financial commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivatives	$ 32,868	$ 32,725	$ (3,903)