Consolidated Statement of Shareholder's Interest (USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Shareholder's Interest [Roll Forward]
Balance at beginning of period		$ 9,653		$ 8,896	$ 9,653	$ 8,896	$ 10,322
Net income	568	364	268	295	1,479	1,214	1,795
Condolidation, Wholly Owned Subsidiary, Parent Ownership Interest, Purchase of Interest by Parent					3	0	0
Other comprehensive income/(loss), net of tax					(86)	143	(221)
Distributions					(445)	(600)	(3,000)
Balance at end of period	10,604		9,653		10,604	9,653	8,896
Shareholder's Interest [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period		5,274		5,274	5,274	5,274	5,274
Net income					0	0	0
Condolidation, Wholly Owned Subsidiary, Parent Ownership Interest, Purchase of Interest by Parent					3	0	0
Other comprehensive income/(loss), net of tax					(60)	0	0
Distributions					0	0	0
Balance at end of period	5,217		5,274		5,217	5,274	5,274
Accumulated Other Comprehensive Income/(Loss) (Note11) [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period		743		600	743	600	821
Net income					0	0	0
Condolidation, Wholly Owned Subsidiary, Parent Ownership Interest, Purchase of Interest by Parent					0	0	0
Other comprehensive income/(loss), net of tax					(26)	143	(221)
Distributions					0	0	0
Balance at end of period	717		743		717	743	600
Retained Earnings [Member]
Shareholder's Interest [Roll Forward]
Balance at beginning of period		3,636		3,022	3,636	3,022	4,227
Net income					1,479	1,214	1,795
Condolidation, Wholly Owned Subsidiary, Parent Ownership Interest, Purchase of Interest by Parent					0	0	0
Other comprehensive income/(loss), net of tax					0	0	0
Distributions					(445)	(600)	(3,000)
Balance at end of period	$ 4,670		$ 3,636		$ 4,670	$ 3,636	$ 3,022