Business Segment Information (Reconciliation of Equity Affiliates' Income) (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Equity affiliates' income		$ 13.8	$ 38.0
Segment Total
Segment Reporting Information [Line Items]
Equity affiliates' income		46.3	38.0
Segment Reconciling Items
Segment Reporting Information [Line Items]
Tax reform repatriation - equity method investment	[1]	$ (32.5)	$ 0.0

[1] (A) For additional information on the impact of the U.S. Tax Cuts and Jobs Act, including our equity affiliate impact, refer to Note 17, Income Taxes.