Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Loss	Treasury Stock at Cost	(Accumulated Deficit) Retained Earnings	Non-controlling Interests
Balance at Beginning of Period at Dec. 31, 2018	$ 10,484	$ 5	$ 8,203	$ (32)	$ (730)	$ 1,980	$ 1,058
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Loss	(289)					(313)	24
Stock-based Compensation	14		14
Dividends	(53)					(53)
Distributions to Noncontrolling Interest Owners	(17)		0	0			(17)
Contributions from Noncontrolling Interest Owners	10						10
Other	(6)		2		(5)		(3)
Balance at End of Period at Mar. 31, 2019	10,143	5	8,219	(32)	(735)	1,614	1,072
Balance at Beginning of Period at Dec. 31, 2019	9,055	5	8,927	(31)	(732)	241	645
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Loss	(4,007)					(3,963)	(44)
Stock-based Compensation	17		17
Dividends	(58)					(58)
Distributions to Noncontrolling Interest Owners	(29)						(29)
Contributions from Noncontrolling Interest Owners	78						78
Other	(10)		(2)	(1)	(8)		(1)
Balance at End of Period at Mar. 31, 2020	$ 5,046	$ 5	$ 8,942	$ (30)	$ (740)	$ (3,780)	$ 649