Consolidated Statements of Stockholders' Equity and Mezzanine Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Preferred Stock
Balance at Sep. 30, 2021	$ 1,342.7	$ 1.1	$ 1,489.1	$ (141.6)	$ (1.5)	$ (4.4)	$ 0.0
Balance, Shares at Sep. 30, 2021		105.2					0.0
Net Income (Loss)	14.0			14.0
Other comprehensive income (loss), net of tax	3.5				3.5
Capital contributions and issuance of common stock	1.5		1.5
Capital contributions and issuance of common stock, Shares		0.5
Equity-based compensation	18.9		18.9
Repurchase of common stock and distributions	(163.8)					(163.8)
Balance at Sep. 30, 2022	1,216.8	$ 1.1	1,509.5	(127.6)	2.0	(168.2)	$ 0.0
Balance, Shares at Sep. 30, 2022		105.7					0.0
Net Income (Loss)	(7.7)			(7.7)
Other comprehensive income (loss), net of tax	15.1				15.1
Capital contributions and issuance of common stock	2.4		2.4
Capital contributions and issuance of common stock, Shares		0.9
Equity-based compensation	22.1		22.1
Repurchase of common stock and distributions	(2.2)					(2.2)
Issuance of Series A preferred stock, net of issuance costs							$ 495.0
Issuance of Series A preferred stock, net of issuance costs, Shares							0.5
Dividends on Series A convertible preferred shares	(3.2)		(3.2)				$ 3.2
Balance at Sep. 30, 2023	1,243.3	$ 1.1	1,530.8	(135.3)	17.1	(170.4)	$ 498.2
Balance, Shares at Sep. 30, 2023		106.6					0.5
Net Income (Loss)	66.4			66.4
Other comprehensive income (loss), net of tax	(18.6)				(18.6)
Capital contributions and issuance of common stock	2.8		2.8
Capital contributions and issuance of common stock, Shares		1.6
Equity-based compensation	20.2		20.2
Repurchase of common stock and distributions	(3.1)					(3.1)
Dividends on Series A convertible preferred shares	(35.7)		(35.7)				$ 8.9
Balance at Sep. 30, 2024	$ 1,275.3	$ 1.1	$ 1,518.1	$ (68.9)	$ (1.5)	$ (173.5)	$ 507.1
Balance, Shares at Sep. 30, 2024		108.2					0.5