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
Net (Loss) Income	(289)					(313)	24
Stock-based Compensation	14		14
Dividends	(53)					(53)
Distributions to Noncontrolling Interest Owners	(17)						(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, 2018	10,484	5	8,203	(32)	(730)	1,980	1,058
Increase (Decrease) in Stockholders' Equity
Net (Loss) Income	(281)
Balance at end of period at Jun. 30, 2019	10,104	5	8,244	(31)	(735)	1,546	1,075
Balance at beginning of period at Mar. 31, 2019	10,143	5	8,219	(32)	(735)	1,614	1,072
Increase (Decrease) in Stockholders' Equity
Net (Loss) Income	8					(10)	18
Stock-based Compensation	21		21
Dividends	(58)					(58)
Distributions to Noncontrolling Interest Owners	(19)						(19)
Contributions from Noncontrolling Interest Owners	11						11
Other	(2)		4	1			(7)
Balance at end of period at Jun. 30, 2019	10,104	5	8,244	(31)	(735)	1,546	1,075
Balance at beginning of period at Dec. 31, 2019	9,055	5	8,927	(31)	(732)	241	645
Increase (Decrease) in Stockholders' Equity
Net (Loss) Income	(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
Balance at beginning of period at Dec. 31, 2019	9,055	5	8,927	(31)	(732)	241	645
Increase (Decrease) in Stockholders' Equity
Net (Loss) Income	(4,394)
Balance at end of period at Jun. 30, 2020	4,662	5	8,966	(29)	(741)	(4,198)	659
Balance at beginning of period at Mar. 31, 2020	5,046	5	8,942	(30)	(740)	(3,780)	649
Increase (Decrease) in Stockholders' Equity
Net (Loss) Income	(387)					(408)	21
Stock-based Compensation	26		26
Dividends	(10)					(10)
Distributions to Noncontrolling Interest Owners	(14)						(14)
Contributions from Noncontrolling Interest Owners	3						3
Other	(2)		(2)	1	(1)
Balance at end of period at Jun. 30, 2020	$ 4,662	$ 5	$ 8,966	$ (29)	$ (741)	$ (4,198)	$ 659