Business Segment Information (Reconciliation of Equity Affiliates' Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Equity affiliates' income	$ 51.2	$ 56.4	$ 197.6	$ 155.5
India Finance Act 2020			33.8
Segment Total
Segment Reporting Information [Line Items]
Equity affiliates' income	51.2	56.4	163.8	155.5
Segment Reconciling Items
Segment Reporting Information [Line Items]
India Finance Act 2020	$ 0.0	$ 0.0	$ 33.8	$ 0.0

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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