UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional paid-in capital	Treasury stock	Accumulated deficit	Total Accumulated Other Comprehensive Income	Noncontrolling interests
Balance, beginning of period at Dec. 31, 2020		$ 1.4	$ 3,364.6	$ (1,368.9)	$ (1,273.3)	$ 205.8	$ 51.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation for equity-classified awards			1.8
Common stock issuances, net of costs			0.0
Net loss	$ (79.7)				(80.1)		0.4
Repurchase of employee common stock relinquished for tax withholding	0.6			(0.6)
Postretirement plans (net of $0.0 tax provisions in each period)	(11.0)					(11.0)
Foreign currency translation adjustment	(0.2)					(0.2)
Distributions to noncontrolling interests							(0.1)
Common stock issuances, net of costs		0.0
Balance, end of period at Mar. 31, 2021	891.5	1.4	3,366.4	(1,369.5)	(1,353.4)	194.6	52.0
Balance, beginning of period at Dec. 31, 2021	1,820.8	1.8	3,745.6	(1,370.3)	(913.2)	297.9	59.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation for equity-classified awards			2.0
Common stock issuances, net of costs			221.9
Net loss	(120.6)				(119.5)		(1.1)
Repurchase of employee common stock relinquished for tax withholding	2.0			(2.0)
Postretirement plans (net of $0.0 tax provisions in each period)	(13.4)					(13.4)
Foreign currency translation adjustment	1.9					1.9
Distributions to noncontrolling interests							(13.8)
Common stock issuances, net of costs		0.1
Balance, end of period at Mar. 31, 2022	$ 1,896.9	$ 1.9	$ 3,969.5	$ (1,372.3)	$ (1,032.7)	$ 286.4	$ 44.1