DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Dec. 31, 2020	Sep. 30, 2020
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	24.0	23.7
Natural Gas Distribution | Long | Physical Commodity
Derivative [Line Items]
Notional amount	4.4	6.0
Energy Services | Long | Physical Commodity
Derivative [Line Items]
Notional amount		5.0
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	25.3	27.5
Energy Services | Short | Physical Commodity
Derivative [Line Items]
Notional amount	7.3
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	1.2	1.8