INFORMATION BY OPERATING SEGMENT - Reconciliation of Consolidated Net Income to Consolidated Net Economic Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Net Income	$ 94.4	$ 52.2	$ 141.5	$ 87.8
Unrealized loss (gain) on energy-related derivative contracts	2.6	(1.7)	(0.4)	(1.3)
Lower of cost or market inventory adjustments	(1.0)	(0.5)	0.2	(0.6)
Realized loss (gain) on economic hedges prior to sale of the physical commodity	0.1	(0.1)	0.1	(0.1)
Acquisition, divestiture and restructuring activities	1.5	1.8	1.9	2.2
Net Economic Earnings (Non-GAAP)	$ 97.6	$ 51.7	$ 143.3	$ 88.0