INFORMATION BY OPERATING SEGMENT - Reconciliation of Consolidated Net Income to Consolidated Net Economic Earnings (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Net Income	$ 45.2	$ 46.9
Unrealized loss (gain) on energy-related derivative contracts	3.8	(4.9)
Lower of cost or market inventory adjustments	(0.1)	0.6
Realized gain on economic hedges prior to sale of the physical commodity	(0.1)	(0.1)
Acquisition, divestiture and restructuring activities	0.1	1.3
Income tax effect of adjustments	(1.4)	1.3
Net Economic Earnings	$ 47.5	$ 45.1