Statement of Changes in Consolidated Equity (unaudited) - USD ($) $ in Millions	Total	Preferred Class A [Member]	Preferred Class B [Member]	Preferred Stock [Member]	Mandatory Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Retained Earnings (Accumulated Deficit) [Member] Preferred Class A [Member]	Retained Earnings (Accumulated Deficit) [Member] Preferred Class B [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2015	$ 14,131			$ 55	$ 3	$ 1,391	$ 10,019	$ 8,834			$ (2,825)	$ (5,431)	$ 2,085
Net income	375							317					58
Other comprehensive (loss) income (C)	(237)											(427)	190
Cash dividends declared:
Preferred share, value		$ (2)	$ (50)						$ (2)	$ (50)
Common share, value	(159)							(159)
Stock-based compensation	73						73
Common stock issued: compensation plans	(23)						(209)				186
Retirement of Treasury stock						(76)	(2,563)				2,639
Reverse stock split						(877)	877
Distributions	(176)												(176)
Other	13												13
Balance at Sep. 30, 2016	13,945			55	3	438	8,197	8,940				(5,858)	2,170
Balance at Jun. 30, 2016	14,529			55	3	1,391	9,877	8,871			(2,647)	(5,215)	2,194
Net income	186							166					20
Other comprehensive (loss) income (C)	(609)											(643)	34
Cash dividends declared:
Preferred share, value		(1)	(16)						(1)	(16)
Common share, value	(80)							(80)
Stock-based compensation	18						18
Common stock issued: compensation plans	(4)						(12)				8
Retirement of Treasury stock						(76)	(2,563)				$ 2,639
Reverse stock split						(877)	877
Distributions	(92)												(92)
Other	14												14
Balance at Sep. 30, 2016	13,945			55	3	438	8,197	8,940				(5,858)	2,170
Balance at Dec. 31, 2016	5,141			55	3	438	8,214	(1,027)				(2,568)	26
Net income	653							653
Other comprehensive (loss) income (C)	241											241
Cash dividends declared:
Preferred share, value		(2)	(51)						(2)	(51)
Common share, value	(107)							(107)
Stock-based compensation	59						59
Common stock issued: compensation plans	25					4	21
Distributions	(14)												(14)
Other	16							15					1
Balance at Sep. 30, 2017	5,961			55	3	442	8,294	(519)				(2,327)	13
Balance at Jun. 30, 2017	5,753			55	3	441	8,262	(567)				(2,454)	13
Net income	119							119
Other comprehensive (loss) income (C)	127											127
Cash dividends declared:
Preferred share, value		$ (1)	$ (17)						$ (1)	$ (17)
Common share, value	(53)							(53)
Stock-based compensation	11						11
Common stock issued: compensation plans	22					1	21
Balance at Sep. 30, 2017	$ 5,961			$ 55	$ 3	$ 442	$ 8,294	$ (519)				$ (2,327)	$ 13