Financing Agreements (Schedule of Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Total	$ 767.0	$ 795.9
Unsecured Debentures [Member]
Debt Instrument [Line Items]
Fair value of unsecured notes	44.8	48.1
Senior Unsecured 5.00% Notes due on February 14, 2025 [Member]
Debt Instrument [Line Items]
Fair value of unsecured notes	303.1	312.4
Senior Unsecured 4.375% Notes due September 2027 [Member]
Debt Instrument [Line Items]
Fair value of unsecured notes	$ 419.1	$ 435.4