Earnings (Loss) Per Share of Common Stock - Reconciliation of Numerator and Denominator for Basic and Diluted Earnings (loss) Per Share Calculation (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income (loss)		$ 23.5	$ 16.8	$ 40.8	$ (24.1)
Less: dividends on Series A convertible preferred shares		(8.9)	0.0	(26.7)	0.0
Less: Earnings allocated to Convertible Preferred Shares		(5.3)	0.0	(5.1)	0.0
Net income (loss) available to common stockholders		$ 9.3	$ 16.8	$ 9.0	$ (24.1)
Weighted average number of common shares outstanding - basic		94,549,000	93,504,000	94,668,000	93,409,000
Basic earnings (loss) per share		$ 0.1	$ 0.18	$ 0.09	$ (0.26)
Net income (loss) available to common shareholders - diluted		$ 9.3	$ 16.8	$ 9.0	$ (24.1)
Stock compensation awards		2,123,000	497,000	1,133,000	0
Weighted average number of common shares outstanding - diluted		96,672,000	94,001,000	95,801,000	93,409,000
Diluted earnings (loss) per share		$ 0.1	$ 0.18	$ 0.09	$ (0.26)
Weighted average number of anti-dilutive Series A convertible preferred shares, options and restricted stock(a)	[1]	55,369,000	4,663,000	57,011,000	4,712,000

[1] Weighted average number of anti-dilutive options is based upon the average closing price of the Company’s common stock on the NYSE for the period.