INFORMATION BY OPERATING SEGMENT - Reconciliation of Consolidated Net Income to Consolidated Net Economic Earnings (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting [Abstract]
Net Income	$ 108.0	$ 100.8	$ 153.2	$ 147.7
Unrealized loss (gain) on energy-related derivative contracts	1.6	2.9	5.4	(2.0)
Lower of cost or market inventory adjustments	0.1	0.1	0.0	0.7
Realized gain on economic hedges prior to sale of the physical commodity	(0.1)	(0.5)	(0.2)	(0.6)
Acquisition, divestiture and restructuring activities	0.1	2.0	0.2	3.3
Income tax effect of adjustments	(0.7)	(1.8)	(2.1)	(0.5)
Net Economic Earnings	$ 109.0	$ 103.5	$ 156.5	$ 148.6