Consdensed Consolidated Statements of Stockholders' Deficit - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred Stock	Preferred Stock Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Common Stock Cumulative Effect, Period of Adoption, Adjustment	Additional Paid-In Capital	Additional Paid-In Capital Cumulative Effect, Period of Adoption, Adjustment	Retained Loss	Retained Loss Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock
Beginning Balance at Dec. 31, 2017	$ (245.3)	$ (0.1)	$ 183.9	$ 0.0	$ 0.6	$ 0.0	$ 1,034.8	$ 0.0	$ (1,336.1)	$ (0.1)	$ (63.0)	$ 0.0	$ (65.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(24.0)		0.0		0.0		0.0		(24.0)		0.0		0.0
Stock-based compensation activity	5.1		0.0		0.0		12.0		(43.4)		0.0		36.5
Net proceeds from issuing equity instruments	0.0
Other comprehensive loss	(4.5)		0.0		0.0		0.0		0.0		(4.5)		0.0
Ending Balance at Dec. 31, 2018	(268.8)		183.9		0.6		1,046.8		(1,403.6)		(67.5)		(29.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(60.3)		0.0		0.0		0.0		(60.3)		0.0		0.0
Stock-based compensation activity	7.0		0.0		0.0		7.6		(11.3)		0.0		10.7
Cumulative effect of adoption of ASU 2018-02	0.0		0.0		0.0		0.0		15.1		(15.1)		0.0
Net proceeds from issuing equity instruments	49.5		0.0		0.1		49.4		0.0		0.0		0.0
Equity instruments issued in connection with Second Lien Term Credit Facility	13.1		0.0		0.0		13.1		0.0		0.0		0.0
Other comprehensive loss	19.1		0.0		0.0		0.0		0.0		19.1		0.0
Ending Balance at Dec. 31, 2019	(240.4)		183.9		0.7		1,116.9		(1,460.1)		(63.5)		(18.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(7.9)		0.0		0.0		0.0		(7.9)		0.0		0.0
Stock-based compensation activity	6.2		0.0		0.0		6.6		(7.3)		0.0		6.9
Net proceeds from issuing equity instruments	0.0
Preferred stock - series D conversion	0.0		(183.9)		0.0		172.5		0.0		0.0		11.4
Other comprehensive loss	5.1		0.0		0.0		0.0		0.0		5.1		0.0
Ending Balance at Dec. 31, 2020	$ (237.0)		$ 0.0		$ 0.7		$ 1,296.0		$ (1,475.3)		$ (58.4)		$ 0.0