EPS under Basic and Diluted Computations (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Earnings Per Share Disclosure [Line Items]
Net income	$ 275		$ 238		$ 470		$ 481
Preferred stock dividends	(14)				(14)
Net income available to common stockholders	$ 261	[1]	$ 238	[1]	$ 456	[1]	$ 481	[1]
Weighted-average common shares outstanding - basic	1,273		1,207		1,272		1,205
Common stock equivalent shares related to stock incentive plans	1		3		1		3
Weighted-average common shares outstanding - diluted	1,274	[2]	1,210	[2]	1,273	[2]	1,208	[2]
Basic EPS	$ 0.20		$ 0.20		$ 0.36		$ 0.40
Diluted EPS	$ 0.20		$ 0.20		$ 0.36		$ 0.40

[1] Net income available to participating securities (unvested restricted shares) was not material for the second quarters or first halves of 2012 or 2011.

[2] Antidilutive stock options and restricted stock awards excluded from the calculation of diluted EPS totaled 59 million and 42 million shares for the second quarters of 2012 and 2011, respectively, and 61 million and 43 million shares for the first halves of 2012 and 2011, respectively.