SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - GAS IN STORAGE (Details) $ in Thousands	Mar. 31, 2019 USD ($) Bcf	Sep. 30, 2018 USD ($) Bcf
Inventory [Line Items]
Gas in Storage, value | $	$ 58,436	$ 184,633
Gas in Storage, Bcf | Bcf	16.5	59.0
Energy Services
Inventory [Line Items]
Gas in Storage, value | $	$ 34,819	$ 90,166
Gas in Storage, Bcf | Bcf	12.1	34.1
Natural Gas Distribution
Inventory [Line Items]
Gas in Storage, value | $	$ 23,617	$ 94,467
Gas in Storage, Bcf | Bcf	4.4	24.9