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		6 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income (loss)		$ 33.7	$ (22.0)	$ 17.3	$ (40.9)
Less: dividends on Series A convertible preferred shares		(8.9)	0.0	(17.8)	0.0
Less: Earnings allocated to Convertible Preferred Shares		(9.0)	0.0	0.0	0.0
Net income (loss) available to common stockholders		$ 15.8	$ (22.0)	$ (0.5)	$ (40.9)
Weighted average number of common shares outstanding - basic		94,436,000	93,475,000	94,210,000	93,362,000
Basic earnings (loss) per share		$ 0.17	$ (0.23)	$ (0.01)	$ (0.44)
Net income (loss) available to common shareholders - diluted		$ 15.8	$ (22.0)	$ (0.5)	$ (40.9)
Stock compensation awards		1,275,000	0	0	0
Weighted average number of common shares outstanding - diluted		95,711,000	93,475,000	94,210,000	93,362,000
Diluted earnings (loss) per share		$ 0.17	$ (0.23)	$ (0.01)	$ (0.44)
Weighted average number of anti-dilutive Series A convertible preferred shares, options and restricted stock(a)	[1]	55,691,000	5,320,000	57,560,000	5,321,000

[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.