Reconciliation between Basic and Diluted EPS Table (Detail) (USD $) In Millions, except Per Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Income (loss):
Net income (loss) attributable to common stockholders	$ (3,051)		$ (26)		$ (2,291)		$ 650
Less: Distributions on participating securities							1
Less: Undistributed income allocated to participating securities							4
Basic	(3,051)		(26)		(2,291)		645
Diluted	$ (3,051)		$ (26)		$ (2,291)		$ 645
Shares:
Average number of common shares outstanding - basic	498		496		498		495
Dilutive effect of stock options and performance-based stock awards							1
Average number of common shares outstanding - diluted	498		496		498		496
Excluded	12	[1]	12	[1]	12	[1]	6	[1]
Income (loss) per common share:
Basic	$ (6.12)		$ (0.05)		$ (4.60)		$ 1.30
Diluted	$ (6.12)		$ (0.05)		$ (4.60)		$ 1.30
Dividends per common share	$ 0.09		$ 0.09		$ 0.27		$ 0.27

[1] Inclusion of the average shares for these awards would have had an anti-dilutive effect.