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, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Earnings Per Common Share
Net income	$ 513		$ 432		$ 984		$ 927
Less: Dividends and undistributed earnings allocated to participating securities	(4)	[1]	(5)	[1]	(9)	[1]	(8)	[1]
Preferred stock dividends	(7)				(7)
Net income available to common shareholders	$ 502		$ 427		$ 968		$ 919
Basic average shares	496,806		495,606		497,137		495,099
Effect of dilutive securities: stock options and stock awards	4,238		3,280		3,616		3,196
Diluted average shares	501,044		498,886		500,753		498,295
Anti-dilutive securities	1,434	[2]	14,294	[2]	1,155	[2]	10,969	[2]
Earnings per share: Basic	$ 1.01		$ 0.87		$ 1.95		$ 1.86
Earnings per share: Diluted	$ 1.00	[3]	$ 0.87	[3]	$ 1.93	[3]	$ 1.86	[3]

[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, have non-forfeitable rights to dividends during the vesting period on a basis equivalent to dividends paid to common shareholders.

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

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