Consolidated Statement of Shareholder's Interest - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 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	358	306
Net Income (Loss) Attributable to Noncontrolling Interest	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	358	306
Other Comprehensive Income (Loss), Net of Tax	172	(482)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	172	(483)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0	1
Distributions	0	(28)
Balance at end of period	12,243	11,162
Shareholder's Interest Attributable to Noncontrolling Interest	1	1
Total Shareholder's Interest	12,244	11,163
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
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	172	(483)
Distributions	0	0
Balance at end of period	(435)	(323)
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period	7,093	5,980
Net income	358	306
Other Comprehensive Income (Loss), Net of Tax	0	0
Distributions	0	(28)
Balance at end of period	7,451	6,258
Parent [Member]
Shareholder's Interest [Roll Forward]
Distributions	0	(28)
Noncontrolling Interest [Member]
Shareholder's Interest [Roll Forward]
Distributions	$ 0	$ 0