Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Equity [Abstract]
Common shares, authorized (in shares)	300,000,000	300,000,000	300,000,000
Shares available for future awards (in shares)	2,400,000	2,400,000
Preferred shares, par value (in usd per share)	$ 0.01	$ 0.01	$ 0.01
Preferred shares, outstanding (in shares)	0	0	0
Treasury Stock, Shares, Acquired		2,800,000
Treasury Stock, Value, Acquired, Cost Method		$ 90.2	$ 59.3	$ 75.2
Shares available for repurchase under authorization		0.2
Common Stock, Dividends, Per Share, Declared	$ 0.15
Preferred shares, authorized (in shares)	10,000,000.0	10,000,000.0	10,000,000.0
Dividends, Common Stock, Cash		$ 28.8	$ 30.6	31.7
Payments of Dividends		$ 29.3	$ 30.7	$ 31.5
Shares purchased to satisfy tax withholding		200,000