Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2020		137,812,559	16,668,521
Beginning Balance at Dec. 31, 2020	$ 87.9	$ 1.4	$ (139.2)	$ 393.7	$ (161.5)	$ (6.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	12.8			12.8
Issuance of common stock related to share-based compensation plans (in shares)		6,497
Issuance of common stock (in shares)		324,212
Issuance of common stock	7.0			7.0
Exercise of vested stock options (in shares)		539,795
Exercise of vested stock options	3.5			3.5
Acquisition of treasury stock related to share-based compensation plans (in shares)			(2,201)
Net change on derivatives designated as cash flow hedges, net of tax	0.5					0.5
Foreign currency translation adjustments	(0.4)					(0.4)
Conversion of preferred shares (in shares)		117,706,400
Conversion of preferred shares	251.5	$ 1.2		250.3
Inducement dividend	(592.3)			(592.3)
Issuance of common stock related to inducement (in shares)		21,582,800
Issuance of common stock related to inducement	487.3	$ 0.2		487.1
Net income	25.8				25.8
Ending Balance (in shares) at Mar. 31, 2021		277,972,263	16,670,722
Ending Balance at Mar. 31, 2021	283.6	$ 2.8	$ (139.2)	562.1	(135.7)	(6.4)
Beginning Balance (in shares) at Dec. 31, 2021		298,320,928	20,094,686
Beginning Balance at Dec. 31, 2021	346.7	$ 3.0	$ (215.2)	628.5	(64.3)	(5.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	$ 10.2			10.2
Issuance of common stock related to share-based compensation plans (in shares)		1,757,955
Exercise of vested stock options (in shares)	77,438	77,438
Exercise of vested stock options	$ 0.4			0.4
Acquisition of treasury stock related to share-based compensation plans (in shares)			(727,768)
Acquisition of treasury stock related to share-based compensation plans	(18.7)
Repurchases of common stock (in shares)			(8,000)
Repurchases of common stock	(0.2)		$ (0.2)
Net change on derivatives designated as cash flow hedges, net of tax	0.1					0.1
Foreign currency translation adjustments	(1.4)					(1.4)
Net income	29.4				29.4
Ending Balance (in shares) at Mar. 31, 2022		300,156,321	20,830,454
Ending Balance at Mar. 31, 2022	$ 366.5	$ 3.0	$ (234.1)	$ 639.1	$ (34.9)	$ (6.6)