DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Jun. 30, 2020	Sep. 30, 2019
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	18.8	27.6
Natural Gas Distribution | Long | Physical
Derivative [Line Items]
Notional amount	10.3	11.6
Energy Services | Long | Physical
Derivative [Line Items]
Notional amount	12.6	44.5
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	(38.4)	(29.6)
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	2.3	5.0