SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NATURAL GAS IN STORAGE (Details) $ in Thousands	Mar. 31, 2021 USD ($) Bcf	Sep. 30, 2020 USD ($) Bcf
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 74,853	$ 167,504
Natural Gas in Storage, Bcf | Bcf	22.8	61.52
Natural Gas Distribution
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 40,083	$ 110,037
Natural Gas in Storage, Bcf | Bcf	9.4	27.2
Energy Services
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 34,439	$ 57,352
Natural Gas in Storage, Bcf | Bcf	13.3	34.3
Storage and Transportation
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 331	$ 115
Natural Gas in Storage, Bcf | Bcf	0.1	0.02