Basis of Presentation and Summary of Significant Accounting Policies - Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Apr. 30, 2025
Accounting Policies [Abstract]
Authorized amount repurchase of common stock					$ 100.0
Share repurchases (in shares)	1,200	905	1,900	905
Aggregate repurchased value, excluding excise taxes	$ 30.0	$ 20.6	$ 45.1	$ 20.6
Shares repurchased, average price per share (in usd per share)	$ 25.54	$ 22.73	$ 24.12	$ 22.73
Remaining authorized repurchase amount	$ 42.3		$ 42.3