Consolidated Statement of Shareholder's Interest - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Shareholder's Interest [Roll Forward]
Balance at beginning of period			$ 11,367	$ 10,604
Net income	$ 340	$ 264	646	576
Net Income (Loss) Attributable to Noncontrolling Interest			0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			646	576
Other Comprehensive Income (Loss), Net of Tax	196	85	(286)	3
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest			1	0
Distributions			(28)	(28)
Balance at end of period	11,698	11,155	11,698	11,155
Shareholder's Interest Attributable to Noncontrolling Interest	1	0	1	0
Total Shareholder's Interest	11,699	11,155	11,699	11,155
Shareholder's Interest [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			5,227	5,217
Net income			0	0
Other Comprehensive Income (Loss), Net of Tax			0	0
Distributions			0	0
Balance at end of period	5,227	5,217	5,227	5,217
Accumulated Other Comprehensive Income/(Loss) (Note10) [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			160	717
Net income			0	0
Other Comprehensive Income (Loss), Net of Tax	196	85	(287)	3
Distributions			0	0
Balance at end of period	(127)	720	(127)	720
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			5,980	4,670
Net income			646	576
Other Comprehensive Income (Loss), Net of Tax			0	0
Distributions			(28)	(28)
Balance at end of period	$ 6,598	$ 5,218	6,598	5,218
Parent [Member]
Shareholder's Interest [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax			(287)	3
Distributions			(28)	(28)
Noncontrolling Interest [Member]
Shareholder's Interest [Roll Forward]
Distributions			$ 0	$ 0