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	50		53			$ (3)	50
Dividends	(386)		(145)				(145)	(241)
Net loss attributable to common stockholders	1,561			1,561			1,561
Net income (loss) attributable to noncontrolling interests	291							291
Other comprehensive income	22				23		23	(1)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,874
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
Balance (in shares) at Mar. 31, 2018		1,579				130
Balance at Mar. 31, 2018	11,926	$ 158	26,729	(14,030)	(475)	$ (3,726)	8,656	3,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards	2		2				2
Stock-based compensation, including the tender of shares	9		9				9
Dividends	(141)		(73)				(73)	(68)
Net loss attributable to common stockholders	869			869			869
Net income (loss) attributable to noncontrolling interests	166							166
Other comprehensive income	11				11		11
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,046
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
Noncontrolling Interest, Period Increase (Decrease)	(12)		(1)				(1)	(11)
Contributions from noncontrolling interest	100		49				49	51
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		1				1
Stock-based compensation, including the tender of shares	26		33			$ (7)	26
Stock-based compensation, including the tender of shares (in shares)						1
Dividends	(216)		(146)				(146)	(70)
Net loss attributable to common stockholders	(41)			(41)			(41)
Net income (loss) attributable to noncontrolling interests	43							43
Other comprehensive income	24				23		23	1
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	26
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
Noncontrolling Interest, Period Increase (Decrease)	100		49				49	51
Balance (in shares) at Mar. 31, 2019		1,582				131
Balance at Mar. 31, 2019	17,841	$ 158	25,963	(12,010)	(594)	$ (3,734)	9,783	8,058
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation, including the tender of shares	10		10				10
Dividends	(73)		(73)				(73)
Net loss attributable to common stockholders	(72)			(72)			(72)
Net income (loss) attributable to noncontrolling interests	(2)							(2)
Other comprehensive income	13				12		12	1
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(61)
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