CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Common Stock	Common Stock	Common Stock Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Common Stock	Treasury Stock	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income	Noncontrolling Interests
Beginning Balance at Dec. 31, 2019	$ 2,672.5		$ 1.4		$ 3,351.1		$ (1,367.3)	$ 597.0	$ 31.6	$ 58.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,873.8)							(1,870.3)		(3.5)
Postretirement plans (net of $0.0 tax provisions in each period)	168.1								168.1
Foreign currency translation adjustment	6.1								6.1
Share-based compensation for equity-classified awards	13.5				13.5
Repurchase of employee common stock relinquished for tax withholding	(1.6)						(1.6)
Distributions to noncontrolling interests	(3.5)									(3.5)
Ending Balance at Dec. 31, 2020	981.3		1.4		3,364.6		(1,368.9)	(1,273.3)	205.8	51.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	371.4							360.1		11.3
Postretirement plans (net of $0.0 tax provisions in each period)	93.1								93.1
Foreign currency translation adjustment	(1.0)								(1.0)
Share-based compensation for equity-classified awards	10.0				10.0
Stock Issued During Period, Value, New Issues	101.9	$ 269.5	0.1	$ 0.3	101.8	$ 269.2
Repurchase of employee common stock relinquished for tax withholding	(1.4)						(1.4)
Distributions to noncontrolling interests	(4.0)									(4.0)
Ending Balance 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]
Net income (loss)	1,319.1							1,297.1		22.0
Postretirement plans (net of $0.0 tax provisions in each period)	(53.8)								(53.8)
Foreign currency translation adjustment	(1.6)								(1.6)
Share-based compensation for equity-classified awards	8.4				8.4
Stock Issued During Period, Value, New Issues		$ 222.0		$ 0.1		$ 221.9
Repurchase of employee common stock relinquished for tax withholding	(2.6)						(2.6)
Distributions to noncontrolling interests	(17.5)									(17.5)
Ending Balance at Dec. 31, 2022	$ 3,294.8		$ 1.9		$ 3,975.9		$ (1,372.9)	$ 383.9	$ 242.5	$ 63.5