Consolidated Statements of Changes in Shareholders' Equity (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, 2010	$ 7,311	$ 41	$ 0	$ 4,479	$ 2,798	$ (7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	555				555
Other comprehensive income (loss)	(2)					(2)
Preferred stock dividends declared	(2)				(2)
Common stock dividends declared	(550)				(550)
Balance at Dec. 31, 2011	7,312	41	0	4,479	2,801	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	537				537
Other comprehensive income (loss)	(3)					(3)
Preferred stock dividends declared	(2)				(2)
Common stock dividends declared	(200)				(200)
Balance at Dec. 31, 2012	7,644	41	0	4,479	3,136	(12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	682				682
Other comprehensive income (loss)	3					3
Preferred stock dividends declared	(2)				(2)
Common stock dividends declared	(500)				(500)
Redemption of preferred stock	(40)	(39)			(1)
Balance at Dec. 31, 2013	$ 7,787	$ 2	$ 0	$ 4,479	$ 3,315	$ (9)