Stockholders' Equity - Earnings Per Share Reconciliation (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income (loss)
Net income (loss) attributable to common stockholders	$ (318)	$ (1,034)
Income (loss) effect of TEUs	(2)	(1)
Basic	(320)	(1,035)
Diluted	$ (320)	$ (1,035)
Shares
Average number of common shares outstanding—basic	551	509
Average number of common shares outstanding—diluted	551	509
Excluded due to anti-dilutive effect	11	10
Net income (loss) per common share
Basic (in usd per share)	$ (0.58)	$ (2.03)
Diluted (in usd per share)	$ (0.58)	$ (2.03)