Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	APIC [Member]	[1]	Retained Earnings [Member]	AOCI [Member]	[2]
Balance at Sep. 30, 2019	$ 1,862.3	$ 0.7	$ 1,083.0		$ 799.2	$ (20.6)
Balance (in shares) at Sep. 30, 2019		68,600,000
Issuance of common stock, net of shares withheld for taxes	(1.2)		(1.2)
Issuance of common stock, net of shares withheld for taxes (Shares)		200,000
Stock-based compensation	5.2		5.2
Other comprehensive income (loss)	3.8					3.8
Net income (loss)	(23.4)				(23.4)
Dividends on Preferred Stock	(6.0)				(6.0)
Balance at Dec. 31, 2019	1,840.7	$ 0.7	1,087.0		769.8	(16.8)
Balance (in shares) at Dec. 31, 2019		68,800,000
Balance at Sep. 30, 2020	1,760.9	$ 0.7	1,100.6		694.3	(34.7)
Balance (in shares) at Sep. 30, 2020		69,000,000.0
Adoption of ASU 2016-13 | ASU 2016-13 [Member]	(4.3)				(4.3)
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

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

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