Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	APIC [Member]	[1]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	AOCI [Member]	[2]
Balance at Sep. 30, 2020	$ 1,760.9	$ (4.3)	$ 0.7	$ 1,100.6		$ 694.3	$ (4.3)	$ (34.7)
Accounting Standards Update [Extensible Enumeration]		Accounting Standards Update201613 [Member]					Accounting Standards Update201613 [Member]
Balance (in shares) at Sep. 30, 2020			69,000,000.0
Issuance of common stock, net of shares withheld for taxes	4.3			4.3
Issuance of common stock, net of shares withheld for taxes (Shares)			400,000
Stock-based compensation	4.9			4.9
Other comprehensive income (loss)	5.5							5.5
Net income (loss)	(220.5)					(220.5)
Dividends on Preferred Stock	(6.0)					(6.0)
Balance at Dec. 31, 2020	1,544.8		$ 0.7	1,109.8		463.5		(29.2)
Balance (in shares) at Dec. 31, 2020			69,400,000
Balance at Sep. 30, 2021	1,742.8		$ 0.7	1,145.0		620.5		(23.4)
Balance (in shares) at Sep. 30, 2021			70,100,000
Issuance of common stock, net of shares withheld for taxes	0.8			0.8
Issuance of common stock, net of shares withheld for taxes (Shares)			300,000
Stock-based compensation	2.8			2.8
Other comprehensive income (loss)	4.0							4.0
Net income (loss)	68.0					68.0
Dividends on Preferred Stock	(6.0)					(6.0)
Balance at Dec. 31, 2021	$ 1,812.4		$ 0.7	$ 1,148.6		$ 682.5		$ (19.4)
Balance (in shares) at Dec. 31, 2021			70,400,000

[1] Additional Paid-in Capital (“APIC”).

[2] Accumulated Other Comprehensive Income (Loss) ("AOCI").