Stockholders' Equity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Net income (loss)
Net income (loss) attributable to common stockholders	$ (3,268)		$ (2,669)
Less distributions on participating securities	1		0
Basic	(3,269)		(2,669)
Diluted	$ (3,269)		$ (2,669)
Shares
Average number of common shares outstanding—basic	507		504
Average number of common shares outstanding—diluted	507		504
Excluded (1)	11	[1]	11	[1]
Net income (loss) per common share
Basic	$ (6.45)		$ (5.30)
Diluted	$ (6.45)		$ (5.30)
Dividends per common share	$ 0.27		$ 0.18

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