Earnings Per Common Share (Computation of Basic and Diluted Earnings Per Share) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended						1 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011		Aug. 31, 2012 Series C Preferred Stock
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 2,136		$ 2,061		$ 1,920
Less: Preferred stock dividends	(26)	[1]	(29)	[1]	(20)	[1]
Less: Dividends and undistributed earnings allocated to participating securities	(8)	[2]	(13)	[2]	(18)	[2]	(8)
Net income available to common shareholders	$ 2,102		$ 2,019		$ 1,882
Basic average common shares	446,245		474,458		492,598
Effect of dilutive securities: common stock options and common stock awards (in shares)	8,910		6,671		3,474
Diluted average shares	455,155		481,129		496,072
Anti-dilutive securities (in shares)	1,855	[3]	5,619,000	[3]	2,382	[3]
Earnings per Common Share:
Basic (in dollars per share)	$ 4.71		$ 4.25		$ 3.82
Diluted (in dollars per share)	$ 4.62	[4]	$ 4.20	[4]	$ 3.79	[4]

[1] Amount for 2012 included $8 million related to Series C preferred stock issued in August 2012. Remaining amount for 2012 and amount for 2011 were related to Series A preferred stock, which was redeemed in October 2012.

[2] 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.

[3] 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.

[4] Calculations reflect allocation of earnings to participating securities using the two-class method, as this computation is more dilutive than the treasury stock method.