Consolidated Statements of Changes in Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2011	$ 14,265	$ 0	$ 5,423	$ 9,310	$ (641)	$ 173
Balance (shares) at Dec. 31, 2011		75
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,161	0	0	1,145	0	16
Other comprehensive income	76	0	0	0	76	0
Distributions	(18)	0	0	0	0	(18)
Balance at Sep. 30, 2012	15,484	0	5,423	10,455	(565)	171
Balance (shares) at Sep. 30, 2012		75
Balance at Dec. 31, 2012	15,910	0	5,423	10,782	(463)	168
Balance (shares) at Dec. 31, 2012	75	75
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,302
Net Income	1,290	0	0	1,274	0	16
Other comprehensive income	240	0	0	0	240	0
Distributions	(16)	0	0	0	0	(16)
Redemption of preferred securities of subsidiaries	(32)	0	0	0	0	(32)
Other equity transactions	(29)	0	(33)	0	0	4
Balance at Sep. 30, 2013	$ 17,363	$ 0	$ 5,390	$ 12,056	$ (223)	$ 140
Balance (shares) at Sep. 30, 2013	75	75