SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - GAS IN STORAGE (Details) $ in Thousands	Sep. 30, 2021 USD ($) Bcf	Sep. 30, 2020 USD ($) Bcf
Public Utilities, Inventory [Line Items]
Natural Gas in Storage | $	$ 193,606	$ 167,504
Bcf | Bcf	46.40	61.52
Natural Gas Distribution
Public Utilities, Inventory [Line Items]
Natural Gas in Storage | $	$ 115,824	$ 110,037
Bcf | Bcf	27.6	27.2
Energy Services
Public Utilities, Inventory [Line Items]
Natural Gas in Storage | $	$ 77,782	$ 57,352
Bcf | Bcf	18.8	34.3
Storage and Transportation
Public Utilities, Inventory [Line Items]
Natural Gas in Storage | $	$ 0	$ 115
Bcf | Bcf	0	0.02