DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Mar. 31, 2021	Sep. 30, 2020
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	22.1	23.7
Natural Gas Distribution | Long | Physical Commodity
Derivative [Line Items]
Notional amount	16.6	6.0
Energy Services | Long | Physical Commodity
Derivative [Line Items]
Notional amount		5.0
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	11.6	27.5
Energy Services | Short | Physical Commodity
Derivative [Line Items]
Notional amount	1.5
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	0.8	1.8