Consolidated Statements of Changes in Shareholders' Equity Statement (USD $) In Millions, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net [Member]
Balance at Dec. 31, 2012	$ 7,644	$ 41	$ 0	$ 4,479	$ 3,136	$ (12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	160				160
Preferred stock dividends declared	(1)				(1)
Common stock dividends declared	(150)				(150)
Balance at Mar. 31, 2013	7,653	41	0	4,479	3,145	(12)
Balance at Dec. 31, 2013	7,787	2	0	4,479	3,315	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	155				155
Common stock dividends declared	(500)				(500)
Balance at Mar. 31, 2014	$ 7,442	$ 2	$ 0	$ 4,479	$ 2,970	$ (9)