Consolidated Statement of Shareholder's Interest - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Shareholder's Interest [Roll Forward]
Balance at beginning of period			$ 11,713	$ 11,367
Shareholder's Interest Attributable to Noncontrolling Interest			1	0
Total Shareholder's Interest			11,714	11,367
Net income	$ 296	$ 340	654	646
Net Income (Loss) Attributable to Noncontrolling Interest			0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			654	646
Other Comprehensive Income (Loss), Net of Tax	(141)	196	31	(286)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent			31	(287)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest			0	1
Distributions			(1)	(28)
Balance at end of period	12,398	11,698	12,398	11,698
Shareholder's Interest Attributable to Noncontrolling Interest	0	1	0	1
Total Shareholder's Interest	12,398	11,699	12,398	11,699
Shareholder's Interest [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			5,227	5,227
Net income			0	0
Other Comprehensive Income (Loss), Net of Tax			0	0
Distributions			0	0
Balance at end of period	5,227	5,227	5,227	5,227
Accumulated Other Comprehensive Income/(Loss) [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			(607)	160
Net income			0	0
Other Comprehensive Income (Loss), Net of Tax	(141)	196	31	(287)
Distributions			0	0
Balance at end of period	(576)	(127)	(576)	(127)
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period			7,093	5,980
Net income			654	646
Other Comprehensive Income (Loss), Net of Tax			0	0
Distributions			0	(28)
Balance at end of period	$ 7,747	$ 6,598	7,747	6,598
Parent [Member]
Shareholder's Interest [Roll Forward]
Distributions			0	(28)
Noncontrolling Interest [Member]
Shareholder's Interest [Roll Forward]
Distributions			$ (1)	$ 0