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
Balance (in shares) at Dec. 31, 2016		1,574				129
Balance at Dec. 31, 2016	$ 9,257	$ 157	$ 26,690	$ (16,540)	$ (548)	$ (3,708)	$ 6,051	$ 3,206
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards (in shares)		4				0
Exercised and vested stock-based awards	5	$ 1	4	0	0	$ 0	5	0
Stock-based compensation, including the tender of shares	35	0	49	0	0	$ (14)	35	0
Stock-based compensation, including the tender of shares (in shares)						1
Restricted Stock Award, Forfeitures, Dividends				1			1
Dividends	(66)							(67)
Net income attributable to common stockholders	776	0		776		$ 0	776	0
Net income (loss) attributable to noncontrolling interests	110	0				0	0	110
Other comprehensive income	113	$ 0	0		105	$ 0	105	8
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	999
Balance (in shares) at Sep. 30, 2017		1,578				130
Balance at Sep. 30, 2017	10,230	$ 158	26,743	(15,763)	(443)	$ (3,722)	6,973	3,257
Balance (in shares) at Jun. 30, 2017		1,577				130
Balance at Jun. 30, 2017	9,993	$ 158	26,734	(16,043)	(456)	$ (3,720)	6,673	3,320
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards (in shares)		1				0
Exercised and vested stock-based awards	0	$ 0	0	0	0	$ 0	0	0
Stock-based compensation, including the tender of shares	7	0	9	0	0	$ (2)	7	0
Stock-based compensation, including the tender of shares (in shares)						0
Dividends	(28)	0	0		0	$ 0	0	(28)
Net income attributable to common stockholders	280	0		280		0	280	0
Net income (loss) attributable to noncontrolling interests	(35)	0				0	0	(35)
Other comprehensive income	13	$ 0	0		13	$ 0	13	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	258
Balance (in shares) at Sep. 30, 2017		1,578				130
Balance at Sep. 30, 2017	10,230	$ 158	26,743	(15,763)	(443)	$ (3,722)	6,973	3,257
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]
Dividends				0
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 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				0
Exercised and vested stock-based awards	8	$ 0	8	0	0	$ 0	8	0
Stock-based compensation, including the tender of shares	59	0	62	0	0	$ (3)	59	0
Stock-based compensation, including the tender of shares (in shares)						0
Dividends	(459)	$ 0	(218)		0	$ 0	(218)	(241)
Tender of shares for stock based awards shares		0				0
Net income attributable to common stockholders	2,117	$ 0		2,117		$ 0	2,117	0
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net			0		0
Net income (loss) attributable to noncontrolling interests	399	0				0	0	399
Noncontrolling Interest, Change in Redemption Value			0	0	0
Other comprehensive income	34	$ 0	0		34	$ 0	34	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	2,550			0
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	0	9	0	0	$ 0	9	0
Stock-based compensation, including the tender of shares (in shares)						0
Dividends	(73)	0	(73)		0	$ 0	(73)	0
Net income attributable to common stockholders	556	0		556		0	556	0
Net income (loss) attributable to noncontrolling interests	108	0				0	0	108
Other comprehensive income	12	$ 0	0		11	$ 0	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]
Adoption of new accounting standard for reclassification of income taxes (refer to Note 11)	$ 0			$ 79	$ (79)		$ 0