Business Segment Information (Reconciliation of Equity Affiliates' Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Equity affiliates' income (loss)	$ (36.9)	$ 42.1	$ 35.3	$ 107.7
Equity method investment impairment charge			79.5	0.0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Equity affiliates' income (loss)	42.6	42.1	114.8	107.7
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Equity method investment impairment charge	$ (79.5)	$ 0.0	$ (79.5)	$ 0.0