Statement of Changes in Consolidated Equity - 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 [Member]	Retained Earnings [Member] Preferred Class A [Member]	Retained Earnings [Member] Preferred Class B [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2013	$ 13,522			$ 55		$ 1,178	$ 7,509	$ 9,272			$ (3,762)	$ (3,659)	$ 2,929
Net income (loss)	(68)							(40)					(28)
Other comprehensive (loss) income (C)	632											491	141
Cash dividends declared:
Preferred share, value	(1)							(1)
Common share, value	(68)							(68)
Stock-based compensation	49						49
Common stock issued: compensation plans	78						(409)				487
Issuance of common stock	575					89	486
Distributions	(55)												(55)
Contributions	44												44
Other	(2)												(2)
Balance at Jun. 30, 2014	14,706			55		1,267	7,635	9,163			(3,275)	(3,168)	3,029
Balance at Mar. 31, 2014	14,374			55		1,267	7,704	9,061			(3,395)	(3,301)	2,983
Net income (loss)	129							138					(9)
Other comprehensive (loss) income (C)	185											133	52
Cash dividends declared:
Common share, value	(36)							(36)
Stock-based compensation	24						24
Common stock issued: compensation plans	27						(93)				120
Distributions	(20)												(20)
Contributions	24												24
Other	(1)												(1)
Balance at Jun. 30, 2014	14,706			55		1,267	7,635	9,163			(3,275)	(3,168)	3,029
Balance at Dec. 31, 2014	14,794			55	$ 3	1,304	9,284	9,379			(3,042)	(4,677)	2,488
Net income (loss)	462							335					127
Other comprehensive (loss) income (C)	(506)											(289)	(217)
Cash dividends declared:
Preferred share, value		$ (1)	$ (34)						$ (1)	$ (34)
Common share, value	(74)							(74)
Stock-based compensation	55						55
Common stock issued: compensation plans	16						(192)				208
Distributions	(71)												(71)
Other	(3)												(3)
Balance at Jun. 30, 2015	14,638			55	3	1,304	9,147	9,605			(2,834)	(4,966)	2,324
Balance at Mar. 31, 2015	13,843			55	3	1,304	9,124	9,520			(2,841)	(5,591)	2,269
Net income (loss)	207							140					67
Other comprehensive (loss) income (C)	656											625	31
Cash dividends declared:
Preferred share, value			$ (17)							$ (17)
Common share, value	(38)							(38)
Stock-based compensation	29						29
Common stock issued: compensation plans	1						(6)				7
Distributions	(42)												(42)
Other	(1)												(1)
Balance at Jun. 30, 2015	$ 14,638			$ 55	$ 3	$ 1,304	$ 9,147	$ 9,605			$ (2,834)	$ (4,966)	$ 2,324