SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - GAS IN STORAGE (Details) $ in Thousands	Mar. 31, 2020 USD ($) Bcf	Sep. 30, 2019 USD ($) Bcf
Inventory [Line Items]
Gas in Storage, value | $	$ 76,353	$ 169,803
Gas in Storage, Bcf | Bcf	27.7	52.6
Energy Services
Inventory [Line Items]
Gas in Storage, value | $	$ 35,502	$ 52,390
Gas in Storage, Bcf | Bcf	20.3	25.6
Natural Gas Distribution
Inventory [Line Items]
Gas in Storage, value | $	$ 40,655	$ 117,413
Gas in Storage, Bcf | Bcf	7.3	27.0
Midstream
Inventory [Line Items]
Gas in Storage, value | $	$ 196
Gas in Storage, Bcf | Bcf	0.1