Statement of Changes in Consolidated Equity (unaudited) - USD ($) $ in Millions	Total	Parent Company Net Investment [Member]	Common Stock [Member]	Additional Capital [Member]	Retained (Deficit) Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Non-controlling Interest [Member]
Balance at Dec. 31, 2015	$ 11,513	$ 11,042				$ (1,600)	$ 2,071
Net (loss) income	(217)	(275)					58
Other comprehensive (loss) income (G)	16					(174)	190
Establishment of defined benefit plans	(2,528)	176				(2,704)
Change in Parent Company net investment	501	501
Distributions	(176)						(176)
Other	3						3
Balance at Sep. 30, 2016	9,112	11,444				(4,478)	2,146
Balance at Jun. 30, 2016	11,851	11,127				(1,456)	2,180
Net (loss) income	10	(10)					20
Other comprehensive (loss) income (G)	(284)					(318)	34
Establishment of defined benefit plans	(2,528)	176				(2,704)
Change in Parent Company net investment	151	151
Distributions	(92)						(92)
Other	4						4
Balance at Sep. 30, 2016	9,112	$ 11,444				(4,478)	2,146
Balance at Dec. 31, 2016	7,697		$ 2	$ 9,531	$ (104)	(3,775)	2,043
Net (loss) income	615				413		202
Other comprehensive (loss) income (G)	(56)					(258)	202
Stock-based compensation	21			21
Common stock issued: compensation plans	37			37
Contributions	56						56
Distributions	(244)						(244)
Other	(8)			(5)			(3)
Balance at Sep. 30, 2017	8,118		2	9,584	309	(4,033)	2,256
Balance at Jun. 30, 2017	8,199		2	9,559	196	(3,803)	2,245
Net (loss) income	169				113		56
Other comprehensive (loss) income (G)	(186)					(230)	44
Stock-based compensation	7			7
Common stock issued: compensation plans	20			20
Distributions	(89)						(89)
Other	(2)			(2)
Balance at Sep. 30, 2017	$ 8,118		$ 2	$ 9,584	$ 309	$ (4,033)	$ 2,256