CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions		Total	Common Stock	Additional Paid-In Capital	Retained Earnings/ (Accumulated Deficit)	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2018		$ (1,234)	$ 4	$ 8,510	$ (6,022)	$ (3,632)	$ (94)
Increase (Decrease) in Stockholders' Equity
Net loss (income)		4,438			4,438
Other comprehensive loss		(98)					(98)
Shares reissuance for ESPP		3		1		2
Share repurchases		(1,409)				(1,409)
Equity-based awards activity, net	[1]	(16)		(16)
Issuance of common stock		6		6
Common stock dividends	[2]	(32)			(32)
Ending balance at Dec. 31, 2019		1,658	4	8,501	(1,616)	(5,039)	(192)
Increase (Decrease) in Stockholders' Equity
Net loss (income)		510			510
Other comprehensive loss		(14)					(14)
Repurchase of partners' equity interest in VIE		18
Shares reissuance for ESPP		4				4
Share repurchases		(197)				(197)
Equity-based awards activity, net	[1]	(3)		(3)
Issuance of common stock		1		1
Common stock dividends	[2]	(297)			(297)
Ending balance at Dec. 31, 2020		1,680	4	8,517	(1,403)	(5,232)	(206)
Increase (Decrease) in Stockholders' Equity
Net loss (income)		2,187			2,187
Other comprehensive loss		80					80
Shares reissuance for ESPP		4		1		3
Share repurchases		(44)				(44)
Equity-based awards activity, net	[1]	12		12
Issuance of common stock		1		1
Common stock dividends	[2]	(320)			(320)
Ending balance at Dec. 31, 2021		$ 3,600	$ 4	$ 8,531	$ 464	$ (5,273)	$ (126)

[1] Includes $(9) million, $(27) million and $(36) million of equivalent shares purchased in lieu of tax withholding on equity compensation issuances for the years ended December 31, 2021, 2020 and 2019, respectively

[2] Dividends per common share were $1.30, $1.20 and $0.12 for each of the years ended December 31,2021, 2020 and 2019, respectively