CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (USD $) In Millions, unless otherwise specified	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income
Balance at end of period at Dec. 31, 2011		$ 1,565	$ 0	$ 13,814	$ 2,481	$ 642
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans and other				(1)
Net income	235				235
Cash dividends declared on preferred stock					(19)
Other comprehensive income, net of tax	(89)					(89)
Common shareholders' equity	17,063
Balance at beginning and end of period at Mar. 31, 2012	18,628			13,813	2,697	553
Balance at end of period at Dec. 31, 2012	17,836	1,565	0	14,123	1,363	785
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans and other				(36)
Net income	183				183
Cash dividends declared on preferred stock					(18)
Other comprehensive income, net of tax	(127)					(127)
Common shareholders' equity	16,273
Balance at beginning and end of period at Mar. 31, 2013	$ 17,838			$ 14,087	$ 1,528	$ 658