DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Mar. 31, 2020	Sep. 30, 2019
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	24.1	27.6
Natural Gas Distribution | Long | Physical
Derivative [Line Items]
Notional amount	20.0	11.6
Energy Services | Long | Physical
Derivative [Line Items]
Notional amount	30.9	44.5
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	(27.0)	(29.6)
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	2.9	5.0