INFORMATION BY OPERATING SEGMENT - Reconciliation of Consolidated Net Income to Consolidated Net Economic Earnings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting [Abstract]
Net Income	$ 10.7	$ 14.1	$ 158.4	$ 155.6
Unrealized loss (gain) on energy-related derivative contracts	4.9	(2.9)	2.9	(3.5)
Lower of cost or market inventory adjustments	(0.1)	(0.4)	0.6	0.0
Realized (gain) loss on economic hedges prior to sale of the physical commodity	(0.3)	2.5	(0.9)	2.6
Acquisition, divestiture and restructuring activities	1.8	3.5	5.1	6.5
Gain on sale of property	0.0	(7.6)	0.0	(7.6)
Income tax effect of adjustments	(2.4)	1.9	(2.9)	0.8
Net Economic Earnings	$ 14.6	$ 11.1	$ 163.2	$ 154.4