Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Common shares, authorized (in shares)	300,000,000				300,000,000	300,000,000.0
Shares available for future awards (in shares)	2,600,000				2,600,000
Preferred shares, par value (in usd per share)	$ 0.01				$ 0.01	$ 0.01
Preferred shares, outstanding (in shares)	0				0	0
Shares withheld for taxes on equity based compensation (in shares)					300,000
Treasury Stock, Shares, Acquired					3,300,000
Treasury Stock, Value, Acquired, Cost Method					$ 125.3	$ 9.2
Shares available for repurchase under authorization					6.5
Common Stock, Dividends, Per Share, Declared	$ 0.15	$ 0.15	$ 0.15	$ 0.15
Preferred shares, authorized (in shares)	10,000,000.0				10,000,000.0	10,000,000.0
Dividends declared to common shareholders					$ 32.6	$ 33.7
Dividends paid					$ 32.6	$ 25.6	$ 0.0