DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Dec. 31, 2019	Sep. 30, 2019
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	27.6	27.6
Natural Gas Distribution | Long | Physical
Derivative [Line Items]
Notional amount	4.9	11.6
Energy Services | Long | Physical
Derivative [Line Items]
Notional amount	46.8	44.5
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	(34.6)	(29.6)
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	3.8	5.0