Stockholders' Equity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Net income (loss)
Net income (loss) attributable to common stockholders	$ (2,669)		$ 460
Less undistributed income allocated to participating securities	0		3
Basic	(2,669)		457
Diluted	$ (2,669)		$ 457
Shares
Average number of common shares outstanding—basic	504		501
Dilutive effect of stock options	0		2
Average number of common shares outstanding—diluted	504		503
Excluded (1)	11	[1]	4	[1]
Net income (loss) per common share
Basic	$ (5.30)		$ 0.91
Diluted	$ (5.30)		$ 0.91
Dividends per common share	$ 0.18		$ 0.09

[1] Inclusion of certain shares would have had an anti-dilutive effect.