CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury
Balance (in shares) at Dec. 31, 2019		585,555,923				44,353,224
Balance beginning at Dec. 31, 2019	$ 3,246	$ 6	$ 4,726	$ (1,251)	$ (33)	$ (202)
Comprehensive income:
Net (loss) income	(1,547)			(1,547)
Comprehensive income (loss)	(1,547)
Stock-based compensation	1		1
Issuance of restricted stock (in shares)		12,397
Cancellation of restricted stock (in shares)		(167,130)
Restricted units granted (in shares)		1,005,976
Restricted units granted	1		1
Tax withholding - stock compensation (in shares)		(383,731)
Balance (in shares) at Mar. 31, 2020		586,023,435				44,353,224
Balance ending at Mar. 31, 2020	1,701	$ 6	4,728	(2,798)	(33)	$ (202)
Balance (in shares) at Dec. 31, 2020		718,795,700				44,353,224
Balance beginning at Dec. 31, 2020	497	$ 7	5,093	(4,363)	(38)	$ (202)
Comprehensive income:
Net (loss) income	80			80
Comprehensive income (loss)	80
Issuance of restricted stock (in shares)		10,067
Cancellation of restricted stock (in shares)		(405)
Restricted units granted (in shares)		2,136,882
Restricted units granted	8		8
Performance units vested (in shares)		1,001,505
Performance units vested	4		4
Tax withholding - stock compensation (in shares)		(748,627)
Tax withholding – stock compensation	(3)		(3)
Balance (in shares) at Mar. 31, 2021		721,195,122				44,353,224
Balance ending at Mar. 31, 2021	$ 586	$ 7	$ 5,102	$ (4,283)	$ (38)	$ (202)