Reconciliation of Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations	$ 223		$ 468		$ 524		$ 992
Effect of dilutive securities	0	[1]	0	[1]	0	[1]	0	[1]
Earnings (loss) from continuing operations - assuming dilution	223		468		524		992
Average common shares outstanding	435.1		432.3		434.7		432.2
Average common shares outstanding - assuming dilution	439.8		435.2		439.7		436.7
Basic earnings (loss) from continuing operations per common share	$ 0.51		$ 1.08		$ 1.20		$ 2.30
Diluted earnings (loss) from continuing operations per common share	$ 0.51		$ 1.08		$ 1.19		$ 2.27
Restricted stock performance share plan
Earnings Per Share [Line Items]
Effect of dilutive securities	4.7	[1]	2.9	[1]	5.0	[1]	4.5	[1]
Stock options
Earnings Per Share [Line Items]
Effect of dilutive securities	$ 0	[1],[2]	$ 0	[1],[2]	$ 0	[1],[2]	$ 0	[1],[2]

[1] Securities are not included in the table in periods when antidilutive.

[2] Options to purchase 10.7 million shares and 16.9 million shares for the three months ended September 30, 2012 and 2011, respectively, and options to purchase 9.4 million shares and 16.9 million shares for the nine months ended September 30, 2012 and 2011, respectively, were not included in the computation of diluted common shares outstanding because their exercise price exceeded the average market price of the Company’s common stock for each respective reporting period.