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	326				326
Preferred stock dividends declared	(1)				(1)
Common stock dividends declared	(500)				(500)
Redemption of preferred stock	(5)	(5)
Balance at Jun. 30, 2013	7,464	36	0	4,479	2,961	(12)
Balance at Dec. 31, 2013	7,787	2	0	4,479	3,315	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	339				339
Common stock dividends declared	(625)				(625)
Balance at Jun. 30, 2014	$ 7,501	$ 2	$ 0	$ 4,479	$ 3,029	$ (9)