Earnings Per Common Share (Computation of Basic and Diluted Earnings Per Share) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Earnings Per Share [Abstract]
Net income	$ 579		$ 490		$ 1,043		$ 917
Less: Preferred stock dividends	(6)		(7)		(13)		(14)
Less: Dividends and undistributed earnings allocated to participating securities	(2)	[1]	(3)	[1]	(4)	[1]	(6)	[1]
Net income available to common shareholders	$ 571		$ 480		$ 1,026		$ 897
Basic average common shares	452,176		481,404		453,240		483,165
Effect of dilutive securities: common stock options and common stock awards	8,864		7,114		8,390		5,980
Diluted average shares	461,040		488,518		461,630		489,145
Anti-dilutive securities	2,330	[2]	5,525	[2]	2,409	[2]	5,678	[2]
Earnings per Common Share:
Basic (per share)	$ 1.26		$ 1.00		$ 2.26		$ 1.86
Diluted (per share)	$ 1.24		$ 0.98		$ 2.22		$ 1.83

[1] Represented the portion of net income available to common equity allocated to participating securities; participating securities, composed of unvested restricted stock and director stock awards, contain non-forfeitable rights to dividends during the vesting period on a basis equivalent to dividends paid to common shareholders.

[2] Represented common stock options and other equity-based awards outstanding, but not included in the computation of diluted average shares because their effect was anti-dilutive.