COMMON STOCK EQUITY - NARRATIVE (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Equity raised through the DRP waiver discount feature	$ 19.0		$ 41.7
Shares issued through the DRP waiver discount feature (in shares)	460		1,014
Equity raised through the DRP	$ 3.7	$ 4.1	$ 13.6	$ 13.8
Number of treasury shares issued from raising of equity through the DRP	92	102	334	381