Earnings per Share (Schedule of Weighted-Average Shares Outstanding) (Details) - shares shares in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Schedule Of Weighted Average Number Of Shares [Line Items]
Basic weighted-average shares outstanding (in shares)	51.2	53.1	54.4
Effect of dilutive securities (in shares)	0.6	0.5	0.8
Diluted weighted-average shares outstanding (in shares)	51.8	53.6	55.2
RSE awards
Schedule Of Weighted Average Number Of Shares [Line Items]
Anti-dilutive awards excluded from the calculation of diluted weighted-average shares outstanding (in shares)	0.0	0.2
RSE awards
Schedule Of Weighted Average Number Of Shares [Line Items]
Effect of dilutive securities (in shares)	0.6	0.5	0.8