Consolidated Statement of Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Accumulated Deficit	AOCI Attributable to Parent [Member]	Common Stock Held in Treasury	Total Stockholder's Equity	Noncontrolling Interests
Contributions from noncontrolling interest	$ 0
Balance (in shares) at Dec. 31, 2017		1,578				130
Balance at Dec. 31, 2017	11,296	$ 158	$ 26,751	$ (14,722)	$ (487)	$ (3,723)	$ 7,977	$ 3,319
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards (in shares)		1
Exercised and issued stock-based awards	8		8				8
Stock-based compensation, including the tender of shares	59		62			$ (3)	59
Dividends	(459)		(218)				(218)	(241)
Net loss attributable to common stockholders	2,117			2,117			2,117
Net income (loss) attributable to noncontrolling interests	399							399
Other comprehensive income	34				34		34	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	2,550
Balance (in shares) at Sep. 30, 2018		1,579				130
Balance at Sep. 30, 2018	13,454	$ 158	26,603	(12,526)	(532)	$ (3,726)	9,977	3,477
Balance (in shares) at Jun. 30, 2018		1,579				130
Balance at Jun. 30, 2018	12,842	$ 158	26,667	(13,161)	(464)	$ (3,726)	9,474	3,368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation, including the tender of shares	9		9				9
Dividends	(73)		(73)				(73)	0
Net loss attributable to common stockholders	556			556			556
Net income (loss) attributable to noncontrolling interests	108							108
Other comprehensive income	12				11		11	1
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	676
Balance (in shares) at Sep. 30, 2018		1,579				130
Balance at Sep. 30, 2018	13,454	$ 158	26,603	(12,526)	(532)	$ (3,726)	9,977	3,477
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption				79	(79)
Contributions from noncontrolling interest	133		65				65	68
Balance (in shares) at Dec. 31, 2018		1,579				130
Balance at Dec. 31, 2018	17,892	$ 158	26,013	(12,041)	(605)	$ (3,727)	9,798	8,094
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards (in shares)		3
Exercised and issued stock-based awards	1	$ 0	1	0	0	0	1	0
Stock-based compensation, including the tender of shares	35	0	42	0	0	$ (8)	34	1
Stock-based compensation, including the tender of shares (in shares)						1
Dividends	(288)		(218)	0		$ 0	(218)	(70)
Adjustments to Additional Paid in Capital, Other	(22)		(22)				(22)
Net loss attributable to common stockholders	(248)	$ 0		(248)		$ 0	(248)
Noncontrolling Interest, Change in Redemption Value			0	0	0
Tender of shares for stock based awards shares		0				0
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net			0		0
Net income (loss) attributable to noncontrolling interests	16	$ 0				$ 0		16
Other comprehensive income	35	$ 0	0		35		35	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(197)			0
Balance (in shares) at Sep. 30, 2019		1,582				131
Balance at Sep. 30, 2019	17,542	$ 158	25,880	(12,289)	(570)	$ (3,735)	9,444	8,098
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling Interest, Period Increase (Decrease)	(12)		(1)				(1)	(11)
Contributions from noncontrolling interest	33		16				16	17
Balance (in shares) at Jun. 30, 2019		1,582				131
Balance at Jun. 30, 2019	17,817	$ 158	25,949	(12,082)	(582)	$ (3,734)	9,709	8,108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation, including the tender of shares	9		9			$ (1)	8	1
Dividends	(72)		(72)				(72)
Adjustments to Additional Paid in Capital, Other	(22)		(22)				(22)
Net loss attributable to common stockholders	(207)			(207)			(207)
Net income (loss) attributable to noncontrolling interests	(27)							(27)
Other comprehensive income	11				12		12	(1)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(223)
Balance (in shares) at Sep. 30, 2019		1,582				131
Balance at Sep. 30, 2019	$ 17,542	$ 158	$ 25,880	$ (12,289)	$ (570)	$ (3,735)	$ 9,444	$ 8,098